There is a curious paradox in modern medicine: some of the interventions that can have the greatest effect on our health happen when we do not feel sick at all.
Getting vaccinated before an infection reaches us. Quitting smoking before heart or lung disease develops. Finding high blood pressure while it is still silent. Having certain screening tests at the right stage of life. Creating routines and environments that make movement, nourishing food, and other healthy behaviors easier. Later in life, it may even mean reviewing whether every medication or test that once seemed reasonable is still helping.
All of that is prevention.
And it may be one of the most powerful ways to give yourself health: not always waiting for a problem to appear before you begin caring for yourself.
Prevention cannot promise a life without disease. Nothing can. Its goal is more realistic and often remarkably valuable: lower the chances of certain illnesses, find some problems when there is a better opportunity to intervene, reduce complications, and avoid medical care that is more likely to burden us than benefit us.
What we do today can change some of the possibilities available to us tomorrow.
Medicine does not begin when disease appears
We often picture medical care as a familiar sequence: a symptom develops, we seek help, someone identifies the problem, and treatment begins.
That part of medicine remains essential. But it is only part of the story.
Prevention asks earlier questions.
Can we keep certain risk factors from developing in the first place? What can we change while a person still feels healthy? Which diseases are worth looking for before symptoms begin? Once a condition exists, what can we do to limit complications? And at what point should we ask whether more testing, more medication, or more treatment might actually create unnecessary harm?
These ideas are often organized into several levels of prevention.
Primordial prevention tries to prevent risk factors themselves from becoming established. Tobacco-control policies, childhood nutrition programs, and communities that make physical activity easier are examples.
Primary prevention acts before disease begins. Vaccination, smoking cessation, physical activity, healthy eating patterns, sun protection, and certain other risk-reduction measures belong here.
Secondary prevention looks for selected diseases or risk factors before symptoms appear. Depending on the person, that may include cancer screening as well as checking blood pressure, cholesterol, or diabetes risk.
Tertiary prevention begins after disease has already developed. The goal is to reduce complications, restore function, and preserve quality of life. Cardiac rehabilitation or rehabilitation after a stroke are examples.
Then there is quaternary prevention, an especially important idea in modern health care. Its purpose is to protect people from overdiagnosis, overtreatment, and medical interventions that may create more burden than benefit.
Taken together, these levels make one point clear: prevention is not a single appointment or test. It evolves with us throughout life.
Prevention can save more lives than we realize
Prevention rarely looks as dramatic as major surgery or a new cancer treatment. When it works, what we often see is precisely what did not happen.
A disease that never developed.
A cancer found earlier.
A heart attack that may have been avoided.
A complication that never had the chance to take away someone’s independence.
Large-scale research helps make that invisible benefit easier to see.
A modeling analysis examining five major cancers in the United States estimated that about 5.94 million cancer deaths were averted between 1975 and 2020. Roughly 4.75 million — about 8 out of every 10 — were attributed to prevention and screening rather than treatment of established disease.
A substantial portion of that benefit came from something that may sound almost ordinary because we have heard about it for so long: reducing tobacco use.
Vaccination tells a similar story. Economic evaluations of large immunization programs have found enormous health and societal returns. In one U.S. childhood cohort, routine immunization prevented millions of illnesses and tens of thousands of estimated deaths while producing savings far greater than the program’s cost.
You do not need to turn your health into a spreadsheet to understand what those numbers mean.
Prevention does not guarantee that disease will never occur.
It can, however, shift the odds in a better direction.
And when even modest reductions in risk are repeated across millions of people and many years, the consequences can be profound.
More screening is not always better prevention
There is an important catch.
If some screening saves lives, it can be tempting to assume that more testing, starting earlier, and testing more often must always be better.
Medicine is rarely that simple.
A screening test can help, but it can also lead to false alarms. It may discover an abnormality that would never have caused harm. It can trigger additional procedures, anxiety, complications, or treatment that ultimately offers little benefit.
That is why preventive recommendations differ according to age, sex, health history, exposures, and sometimes personal preferences.
A mammogram, colonoscopy, PSA test, or low-dose CT scan for lung cancer is not simply “good” or “bad.” Its value depends on who is being tested, when, how often, and whether the expected benefits are likely to outweigh the potential harms.
Medical organizations themselves sometimes disagree about the boundaries. The scientific material provided for this article, for example, notes differences among guidelines about when to begin some forms of cancer screening.
That disagreement does not make prevention meaningless.
It makes thoughtful prevention necessary.
Some decisions are strongly recommended for most people in a particular group. Others should include a conversation about personal risk, expectations, priorities, and preferences.
That conversation is part of preventive medicine too.
Your everyday habits are part of preventive medicine
Prevention does not happen only in a doctor’s office.
It happens in the grocery store, in the kitchen, on the sidewalk, during a break at work, at bedtime, and in decisions about tobacco and other harmful exposures.
The scientific sources provided for this article describe regular physical activity, healthy eating patterns, maintaining a healthy weight, smoking cessation, sun protection, vaccination, and other measures as important forms of primary prevention.
Tobacco offers one of the clearest examples.
Stopping smoking can produce meaningful health benefits even after years of use. The evidence summarized in the provided material indicates that quitting can add years to life expectancy and that part of the excess cardiovascular risk begins to fall relatively soon afterward.
Knowing that, however, is not the same as being able to act on it.
Telling someone to “eat better,” “exercise,” or “quit smoking” takes seconds. Making those recommendations fit into a life shaped by work schedules, children, stress, finances, culture, habits, transportation, and decades of routine is much harder.
A useful preventive strategy therefore begins with a more practical question:
What change could I realistically continue in the life I have now?
For one person, it may be walking during part of a lunch break several days each week.
For another, it may mean preparing one additional meal at home.
Someone trying to stop smoking may benefit from getting professional help rather than attempting another unsupported quit.
For someone else, the next step may simply be scheduling a preventive visit that has been postponed for years.
Prevention becomes more useful when it moves from an abstract ambition to a repeatable action.
Prevention changes as we age
The questions worth asking at 25 are not exactly the questions worth asking at 50 or 75.
Earlier in life, much of the opportunity lies in keeping risk factors from becoming deeply established — shaping patterns of food, movement, tobacco exposure, and other behaviors that may influence health for decades.
As we move through adulthood, selected risk assessments and screening programs become more relevant. The materials provided for this article include recommendations involving blood pressure, diabetes, cervical cancer, breast cancer, colorectal cancer, lung cancer, prostate cancer, osteoporosis, and abdominal aortic aneurysm, among others.
Prevention does not stop in older age.
Its emphasis may simply change.
Later in life, preserving function, preventing complications, and reviewing medications may become increasingly important. So does asking whether every intervention continues to provide enough benefit to justify its risks and burdens.
That is where quaternary prevention becomes particularly useful.
Over the years, people can accumulate diagnoses, prescriptions, tests, and follow-up plans. Eventually, adding one more intervention is not automatically the best answer. Good preventive care sometimes means reviewing the entire picture and asking what is still necessary.
That is not an invitation to stop medications on your own.
It is a reminder that avoiding unnecessary medical care can also be a form of health care.
A preventive plan can begin with a conversation
You do not need to memorize every screening guideline to take an active role in preventive health.
A few questions can start a much more useful conversation at your next visit:
Which health problems am I most likely to develop?
Which vaccines are appropriate for me now?
Which screening tests make sense at my age and with my history?
Are there tests I do not need yet — or may no longer need?
Which health behavior would give me the greatest potential benefit?
Should any of my long-term medications be reviewed?
Questions like these move prevention away from generic checklists and toward a plan that actually fits a person.
They can also help us avoid two extremes.
One is neglect: doing nothing until disease forces us to respond.
The other is obsession: trying to test, measure, and control every possible aspect of the body.
Between those extremes is a more thoughtful form of preventive medicine — one that uses evidence, acknowledges uncertainty, adjusts decisions to individual risk, and remembers that life cannot be organized entirely around avoiding illness.
We prevent disease so that we can live.
We should not spend our entire lives living only to prevent disease.
Giving yourself health means thinking ahead
One of the challenges of prevention is that many of its benefits belong to a future version of ourselves.
Today, we take a walk.
Today, we skip a cigarette.
Today, we get vaccinated.
Today, we ask whether a screening test is due.
Today, we review a medication.
The benefit may emerge months, years, or decades from now. We may never know which illness did not happen or which complication was avoided because of something we chose to do earlier.
That uncertainty does not erase the value of prevention.
Prevention is a way of widening our possibilities: more chances to preserve mobility, independence, energy, and time with the people who matter to us.
At Dr. Dándote Salud, we will continue exploring this way of thinking about health. Future articles will look more closely at the different levels of prevention, age-appropriate screening, vaccination, cardiovascular health, tobacco, nutrition, movement, and an equally important question: when can doing less medicine actually help us care for health better?
I invite you to explore those articles and gradually build your own understanding of preventive health — not in pursuit of perfect health, but to make better-informed choices today that may create better possibilities tomorrow.
Choose Health. Choose Life.
Scientific sources
The sources below support the information presented and are available for readers who would like to explore the evidence in greater depth.
Key readings
- Goddard KAB, Feuer EJ, Mandelblatt JS, et al. Estimation of Cancer Deaths Averted From Prevention, Screening, and Treatment Efforts, 1975-2020. JAMA Oncology. 2025.
- Lai X, Abbas K, Pouwels KB, et al. Global, Regional, and National Impact of the Expanded Programme on Immunization Against 14 Pathogens From 1974 to 2024: An Economic Evaluation. The Lancet Global Health. 2026.
- Tesser CD. Why Is Quaternary Prevention Important in Prevention? Revista de Saúde Pública. 2017.
Additional scientific sources
- Carrico J, La EM, Talbird SE, et al. Value of the Immunization Program for Children in the 2017 US Birth Cohort.Pediatrics. 2022.
- Rigotti NA, Kruse GR, Livingstone-Banks J, Hartmann-Boyce J. Treatment of Tobacco Smoking. JAMA. 2022.
- Davidson KW, Mangione CM, et al. Collaboration and Shared Decision-Making Between Patients and Clinicians in Preventive Health Care Decisions and US Preventive Services Task Force Recommendations. JAMA. 2022.
- Scott IA, Hilmer SN, Reeve E, et al. Reducing Inappropriate Polypharmacy. JAMA Internal Medicine. 2015.