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Longevity · Lesson 1 of 43 · 11 min

What 80 to 120 Actually Depends On

What decides whether your late years are strong, how big each lever is, and what is not yours to move

The goal: late years you can live in

Picture yourself at 85: taking the stairs, carrying your own groceries, getting up off the floor, traveling, running your own life. Much of what decides that is in reach. Across the biggest studies, having all of the basic habits rather than none is worth somewhere between 9 and 24 extra years, and the same habits add years lived free of disease, not only years. The National Institute on Aging says the evidence suggests that people who exercise regularly not only live longer, but also may live better, with more years free of pain or disability.

What the habits together are worth

The clearest numbers come from two large groups of American nurses and health professionals (Li and colleagues, 2018). Five habits were counted: never smoking, a body mass index (weight for height, lesson 15) of 18.5 to 24.9, at least 30 minutes a day of moderate to vigorous activity, a diet in the top 40 percent for quality, and drinking no more than moderately. At age 50, women with all five were estimated to live 14.0 years longer than women with none, and men 12.2 years longer. The authors estimate that 60.7 percent of the deaths in those groups were attributable to missing the five habits. The extra years were mostly healthy ones: at 50, women with four or five of the habits could expect 34.4 more years free of diabetes, heart disease and cancer, against 23.7 for women with none; for men it was 31.1 against 23.5.

Independence has a number too. In one large study of 11,804 adults aged 65 and over in China, men with three or four healthy habits in diet, activity, smoking and alcohol could expect about 2.5 more years without needing help with daily life than men with none or one, and women about 2.1; habits and supportive social conditions together came to about 3.9 years.

A 2024 study of 276,132 US veterans counted eight habits, adding sleep, stress, social connection and no opioid use disorder; all eight against none was worth 24.0 years for men and 20.5 for women. Diet has a number of its own: a 2022 model built on world disease data estimated that a US 20-year-old who moved from a typical Western diet to the best-supported one and kept it up would gain 10.7 years (women) or 13.0 years (men), a population estimate, not a personal forecast; lesson 9 has the detail.

The levers, one by one

Most of these numbers come from observational studies, so they are good estimates of size, not promises. The well-supported list is short: do not smoke, do not carry obesity, keep blood pressure and blood sugar in range, eat mostly plants, move and lift, drink little, sleep regularly, stay close to people.

1. Smoking: more than 10 years. In a US study of about 200,000 adults, people who smoked lost more than 10 years of life expectancy against people who never had, and quitting before 40 removed about 90 percent of the extra risk. If you smoke, this is your first project: lesson 7.
2. Body weight: 2 to 10 years. In 900,000 adults, a BMI of 30 to 35 cut median survival by 2 to 4 years, and 40 to 45 by 8 to 10 years, which the authors call comparable with the effects of smoking. A pooling of 239 studies found the risk per unit larger when weight was measured in younger adults. Lesson 15.
3. Blood pressure: about 5 years. The 2023 Global Burden of Disease study ranks high systolic blood pressure (the top number in a reading) first among 88 risk factors for healthy years lost worldwide, ahead of fine particle air pollution, high blood sugar and smoking. At 50, people with normal blood pressure lived about 5 years longer than people with high blood pressure, and the men among them spent about 7 more years free of heart disease and stroke. Lesson 13.
4. Blood sugar: about 6 years. Across 97 studies, a 50-year-old with diabetes died about 6 years earlier than one without. Lesson 13.
5. Diet: up to 11 to 13 years if started at 20. The 2022 model above. Lesson 9.
6. Movement and fitness. In 122,007 patients given a treadmill test, fitness was tied to lower death rates with no upper limit of benefit found. Movement also keeps people walking: in a trial of 1,635 inactive adults aged 70 to 89 with some physical limits, an aerobic, strength and flexibility program cut the share who lost the ability to walk 400 meters over about 2.6 years from 35.5 to 30.1 percent. Lesson 3 and lesson 4.
7. Alcohol. About 178,000 Americans a year die from excessive drinking. Newer reviews that correct for how the older habit studies were built find no survival benefit from light drinking, so the habit is not drinking heavily, never drinking for your health. Lesson 8.
8. Sleep: 2 to 5 years. In 172,321 US adults, people with all five good sleep habits could expect 4.7 more years at 30 (men) or 2.4 (women) than people with one or none, and nearly 8 percent of deaths were attributable to poor sleep. Lesson 12.
9. People. Across 148 studies, people with stronger relationships had a 50 percent higher chance of being alive at follow-up. Lesson 17.

Most of the best-known longevity voices build on this same list and argue about the extras: protein, supplements, drugs and tests. Lesson 19 grades them against the guidelines.

What is not up to you, and how big it is

• Income: 10 to 15 years. Using 1.4 billion US tax and death records, Chetty and colleagues found in 2016 that the richest 1 percent of men lived 14.6 years longer than the poorest 1 percent, and women 10.1 years longer.
• Education: 8.5 years. Case and Deaton, two economists, found Americans with and without a four-year degree pulling apart since the 1990s, to an 8.5 year gap in adult life expectancy by the end of 2021. Two thirds of American adults have no four-year degree.
• Sex: about 5 years. In 2024, US life expectancy at birth was 76.5 for men and 81.4 for women, a gap of 4.9 years.
• Place. The United States fell from 35th (men) and 19th (women) in the world for life expectancy in 1990 to 46th and 47th in 2021. Hawaii would rank 28th and 22nd as a country; Mississippi for men and West Virginia for women would rank 107th and 99th.
• Genes: less than you think, and argued over. Heritability, the share of the difference between people down to genes, is about a quarter for lifespan in twin studies and well under 10 percent in a 2018 family-tree study of hundreds of millions of people. A January 2026 paper in Science argues it is above 50 percent for deaths from aging itself; a 2025 study of about 490,000 UK adults found that genetic risk scores for 22 diseases explained under 2 percentage points of the differences in who died, against 17 for environment and habits. People who reached 80 free of cancer, heart disease and brain disease carried no known longevity gene variants, only lower genetic risk for Alzheimer disease and heart disease. Sisters and brothers of people who reached 110 were about three to four times more likely to reach 90.
• Luck. A 2015 analysis tied most of the difference in cancer risk between tissues to random copying errors as cells divide, which the authors called bad luck. Later work found most individual cancers still have preventable causes, so some risk is random, not most.

What this means is not that the habits are small. Among the poorest quarter of Americans, life expectancy differed by about 4.5 years depending on where they lived, and the places where poor people lived longest were the places where fewer of them smoked, not the places with more access to medical care (Chetty's study). Researchers also sort the wear of aging into twelve hallmarks (lesson 42), but the studies in this lesson counted years in people, not hallmarks.

The aim is the part the evidence covers: late years in which you move easily, pain does not run the day, and you are strong and sharp enough to do what you want. Read lesson 2 next: it turns this list into one change you can start this week. If you smoke, read lesson 7 straight after it. Free and cheap checks, quitlines and clinics are in lesson 16.

What you can do

• This week: Turn your lowest habit score into one change this week. If you smoke, that is your first project; otherwise lesson 2's five questions pick the first step. People with all five habits at 50 were estimated to live 12 to 14 years longer.
• At your next visit: Ask for your blood pressure and blood sugar numbers. Blood pressure at any age; blood sugar from 35, or sooner with extra weight plus a risk factor. High blood pressure is the world's top risk factor for healthy years lost.
• Skip: Skip anything sold as a route to 120. The longest validated life is 122 years, life past about 110 is barely studied, and a 2024 Nature Aging analysis found radical life extension implausible this century unless aging itself can be slowed.

Keep it going

• Score yourself tonight, straight after dinner. Five habits on one line, each marked yes or no.
• Too tired? Mark only the habit you doubt most, and finish tomorrow.
• Rescore yourself on the first of each month. Five of five is the goal; the body number inside it is BMI, 18.5 to 24.9 in Li's study.