Why we think we’ll live forever

How long do you expect to live? It’s a question most of us encounter more often than we realise. Health apps, pension calculators and insurance tools routinely estimate our lifespan, presenting the answer as a neat statistic. But according to research from London Business School, the way those numbers are framed can profoundly shape how long life feels, and the decisions we make as a result.

David Faro, Associate Professor of Marketing at London Business School, began exploring this question after a moment of personal surprise. While browsing a life expectancy calculator at the age of 50, he was shown two pieces of information side by side. One stated that, based on average statistics, he was expected to live until the age of 83. The other said he had 33 years left.

“Eighty‑three sounded fine,” Faro recalls. “I imagined retirement, grandchildren, a normal old age.” But the phrase “33 years left” landed very differently. “Suddenly it felt short. I started thinking about everything I still wanted to do, and whether it would all fit.”

Time-left versus an age frame

That contrast became the foundation for his research examining how people respond to two common ways of presenting life expectancy: an age frame (living until a certain age) and a time‑left frame (having a certain number of years remaining). The results were striking. When people were shown their life expectancy as time left, they consistently reported that their total life felt shorter than when the same information was expressed as an age.

The difference was not just emotional. The frame people encountered changed how they thought about goals, priorities, and trade‑offs. David describes this as a form of “mental bucket listing.” When life is presented as an amount of time, say 20, 30 or 40 years, people naturally begin to ask what will fit into that span. Which ambitions are realistic? Which experiences matter most? What might need to be postponed, or abandoned altogether?

Age, by contrast, is a point in time rather than a quantity of time. It is associated with milestones such as retirement, grandchildren, career stages, but it does not prompt the same accounting mindset. As a result, it places less psychological pressure on people to prioritise.

The researchers found that this effect was particularly strong for people in midlife and beyond. For participants in their mid‑40s, the time‑left frame made life feel noticeably shorter, while younger participants were largely unaffected. A 25‑year‑old told they have 60 more years ahead tends to experience that as an abundance of time, but would bring about very different reflections for someone who has already lived most of those years.

Healthy life expectancy

The effect also extended beyond total lifespan to healthy life expectancy, or the number of years people can expect to live in good health before chronic conditions associated with ageing emerge. Whether the information referred to living healthily “until age 70” or “for 20 more years” produced the same pattern, the time‑left framing made that period feel shorter and more finite.

These psychological shifts can have meaningful behavioural consequences. In one field experiment conducted with a health‑engagement app, David explained how users received information about their healthy life expectancy framed either as age or time left. Those shown the time‑left version were significantly more likely to click through to a health assessment and to complete it, a process that required time and personal information. Simply changing how longevity was communicated increased engagement with preventative health behaviours, says David.

Which is better?

The findings raise important questions for organisations and policymakers. Health campaigns, insurance communications and digital wellbeing tools often rely on age‑based statistics because they are familiar and easy to communicate. But if the goal is to motivate action, to encourage people to engage with their health, make changes earlier, or take risks seriously, time‑left framing may be more effective, particularly for older audiences.

There are also personal implications. David suggests that there is no single “natural” way to think about life expectancy. The frames we encounter shape our perceptions, often without us noticing. Becoming aware of those frames can help individuals reflect more deliberately on how they plan their time, careers and relationships.

“If you think in terms of how many healthy summers you might have left, or how much time remains for certain experiences, you may make different choices,” he says. “You might prioritise family, travel, or health in ways you wouldn’t if you were only thinking in terms of age.”

The research highlights a simple but powerful insight. How we describe the length of our lives can change how long life feels and, in turn, how we choose to live it.