What do you want to be able to do at age 85?

One of the things that strikes me as a doctor is the enormous difference between people of the same age. I have patients in their eighties who still work in the garden, cycle regularly and move through the world in a way that makes them seem barely 65. Others have become frail. Getting out of a chair takes effort, walking any distance is difficult and a minor infection can be enough to leave them dependent on help. Chronological age tells us something, but not nearly everything.

We see this variation outside the consultation room too. The Netflix documentary Live to 100: Secrets of the Blue Zones contains memorable images of older people remaining remarkably capable. There is a Japanese man moving himself along using only his arms, while elsewhere an older man still rides on horseback. We see people gardening, walking over uneven terrain and repeatedly getting up and down from the floor.

The Blue Zones should not be treated as a blueprint for longevity, and a documentary inevitably tells a simpler story than the science allows. Genetics, healthcare, income, living conditions and chance all influence how we age. Still, these images challenge the assumption that advanced age must inevitably mean passivity and dependence.

What does a long life look like to you?

I sometimes ask people who come to my consultation a question that initially seems to have little to do with medicine: What would you still like to be able to do when you are 85?

The first response is often a brief silence. Most of us are more accustomed to thinking about the next appointment, blood test or number on the scale than about an ordinary day several decades from now.

Then the answers emerge. One person wants to continue living at home. Another wants to work in the garden or walk to the shops. Someone wants to get down on the floor to play with future grandchildren—and be able to get back up again. Others hope to keep cycling, travelling, cooking for friends or walking through a new city without planning every step around a bench.

These answers tell me more than “I want to stay healthy.” Health remains abstract until we connect it to something we value. Carrying our own shopping, climbing the stairs, remembering a conversation and travelling independently may sound ordinary, but these abilities allow us to continue shaping our own lives.

Lifespan is only part of the story

Lifespan is simply the number of years we are alive. It is easy to measure, which is one reason it receives so much attention. We can compare average life expectancy between countries, follow how it changes over time and celebrate when fewer people die prematurely. Living longer is a real achievement, particularly when those additional years have been gained by preventing deaths from infections, cardiovascular disease, cancer or complications of childbirth.

There is also a more personal reason why we are drawn to longevity: most of us do not particularly want to die. Even if we accept death as part of life, the prospect of our own ending—or that of someone we love—can be frightening. Wanting more time is deeply human. And we also want to be able to use that time: to move, think, connect, contribute and enjoy being alive. Life is something to be lived as well as prolonged.

This brings us to healthspan: the period of life in which we remain in reasonably good health, with enough physical and mental capacity to participate in our own lives. It does not require the complete absence of disease. Someone can live well with hypertension, arthritis or diabetes when those conditions are properly managed. Conversely, a person may have few formal diagnoses yet still be severely limited by weakness, exhaustion, pain or isolation.

Modern medicine has become increasingly good at preventing early death and helping people live with conditions that would once have shortened their lives. This is an enormous achievement. Yet keeping someone alive and keeping them well enough to live independently are not quite the same task.

What are we treating people for?

A person may survive a heart attack because of rapid treatment, medication and cardiac surgery, yet become increasingly restricted by loss of strength, poor fitness or fear of physical activity. Someone may have excellent blood pressure readings while gradually losing the muscle needed to climb the stairs. Another person may take medication that successfully controls several diseases but feel too exhausted or physically limited to use the years that treatment has helped preserve.

Sometimes medicine is quite literally what makes the rest of life possible. Lowering blood pressure reduces the risk that a stroke or heart attack will take away part of someone’s future. Treating diabetes helps protect the eyes, kidneys, nerves and blood vessels—and all the possibilities that depend on them.

These treatments serve a wider purpose: preserving the person’s life and, as far as possible, their ability to live it. Medicine can treat illness, reduce risk and sometimes restore lost function. Strength, endurance, supportive relationships and daily movement require attention beyond the prescription.

The reserve we rarely notice

One useful way to understand the differences we see in later life is through the idea of functional reserve. Our bodies can usually do more than daily life requires. We do not need our full muscular strength to stand up from a chair, nor our maximum cardiovascular capacity to walk around the supermarket. The difference between what our body can do and what a task demands is our reserve.

When that reserve is large, daily life feels relatively easy. We can carry shopping bags, climb several flights of stairs or recover from an infection without reaching our limits. If the lift stops working, it is inconvenient rather than a crisis. If we stumble, we may have enough strength, balance and reaction speed to recover before we fall.

Ageing gradually reduces some of this reserve. Muscle mass, bone density, aerobic capacity, balance and recovery tend to decline, although the speed and extent vary enormously. Chronic disease, prolonged inactivity, poor nutrition and periods of bed rest can reduce it further.

We may not notice the loss while plenty of reserve remains. A person can lose considerable strength and still stand up from a chair. The change becomes visible when their capacity approaches the minimum required for the task. Standing then requires pushing with both hands. A suitcase becomes too heavy. An infection leads to several weeks of lost independence.

Hospital admissions can therefore affect older people profoundly. Alongside the illness, days spent mainly in bed, eating less and barely using the muscles can further reduce an already limited reserve. Someone may recover medically without fully returning to their previous level of function.

Building capacity matters even when we do not need all of it today. Stronger legs create more distance between what we can do and what daily life asks of us. Greater cardiovascular fitness gives the heart and lungs more room to cope with hills, illness, surgery and the demands of getting older.

Reserve also exists beyond strength and fitness. Cognitive capacity helps us manage change and remain independent. Relationships provide practical and emotional support. Sleep and adequate nutrition affect how well we maintain and recover our physical and mental resources.

We do not all begin from the same place

It is tempting to look at an active 85-year-old and conclude that they must have made better choices. Reality is more complicated. Some people live with genetic conditions, disability, chronic pain or serious illness despite doing everything “right.” Others have physically demanding jobs that wear down the body. Safe places to walk, time to exercise, money for nutritious food and access to healthcare are not distributed equally.

Chance remains part of the story. A fall, infection, cancer diagnosis or period of severe stress can alter someone’s health in ways no daily routine could have prevented. Remaining fit into old age is not proof of superior discipline, just as becoming frail is not a personal failure. Our habits influence our future without giving us control over it. They can shift the odds and affect the capacity with which we meet whatever happens.

Training for the life you want

The question about age 85 becomes useful when we translate it into something concrete. Imagine yourself at that age, during an ordinary week. Where would you like to live? Would you like to walk somewhere, prepare your own food, play music, travel, care for a garden or sit on the floor with a child? Who do you hope will still be part of your life?

Then consider what those activities might require from you.

Walking through cities or hiking on holiday asks for cardiovascular fitness, leg strength and balance. Gardening requires mobility and the ability to move towards the ground and rise again. Travelling independently draws on endurance, confidence, adaptability and cognitive capacity.

This gives our habits a purpose beyond improving numbers on a health report. “Exercise more” is vague. Maintaining enough strength to rise from the floor gives strength training a reason. Improving fitness feels more relevant when it means being able to explore a new place on foot.

There is a risk in talking about healthspan that health begins to sound like a retirement plan: exercise, eat correctly and give up enjoyable things now so that an older version of ourselves might benefit decades later. Yet many of the things that preserve future capacity also improve life much sooner. Movement can make the body feel more capable today. Better sleep can change tomorrow morning. Shared meals, time outdoors, meaningful work and good relationships are already part of a worthwhile life.

Nor does every decision have to serve longevity. Sometimes we stay up late because the conversation is worth it. We eat for pleasure as well as nutrition. We rest instead of exercising because we are genuinely tired. Turning life into one long programme for preventing death would cause us to miss much of the life we were trying to protect.

The broader direction matters more than an isolated choice. Are we regularly using our muscles, or slowly arranging our days so that we barely need them? Are we maintaining our capacity to walk, lift, balance and recover? Are we keeping relationships and interests alive?

We cannot know whether we will reach 85, nor can we guarantee what condition we will be in if we do. That uncertainty is not a reason to abandon the question. It is a reason to let the answer influence how we live now, without postponing life until some imagined healthier future. Medicine can help us gain years. The wider work of health is to preserve as much life as possible within those years.

So, what would you still like to be able to do at 85?

And what might help you remain able to do it?

Continue your Health Shift

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Worth watching: ageing with possibility

Live to 100: Secrets of the Blue Zones

This four-part Netflix documentary visits communities in Okinawa, Sardinia, Ikaria, Nicoya and Loma Linda where many people remain active into advanced age. It should not be treated as a scientific blueprint for longevity, but it offers a vivid illustration of how capable, connected and engaged later life can sometimes remain. Watch on Netflix

References and further reading

• World Health Organization. Healthy Ageing and the Decade of Healthy Ageing (2021–2030).

• American College of Lifestyle Medicine. Lifestyle Medicine Core Competencies.

• Lee IM, et al. "Effect of physical inactivity on major non-communicable diseases worldwide." The Lancet. 2012.

• Lally P, van Jaarsveld CHM, Potts HWW, Wardle J. "How are habits formed? Modelling habit formation in the real world." European Journal of Social Psychology. 2010.

• National Institute on Aging. Healthy Aging.