We are entering an age when living to 100 is no longer a statistical quirk but a genuine possibility. Yet our retirement plans remain suitable for life expectancy in the 20th century: retire at 65, spend maybe 15-20 years in leisure, then bow out. That model is obsolete.

Consider this: according to one recent analysis, there is a 19% chance that a healthy non-smoking member of a couple will reach age 100. In South Africa and elsewhere people are routinely spending 26 years in retirement compared with an earlier average of 19.

The consequence is clear: the longer we live, the longer our “retirement” phase will be, and the more fragile our financial security becomes if we apply old rules.

What needs to shift? Three major attitudes.

First, the retirement horizon must extend. If you assume retirement at 65 and death at 85 you are planning for 20 years. But if you live to 100 you might be planning for 35 or more. Those extra fifteen years changes every calculation: how much to save, how you invest, how you draw down. As one commentator warns: “People’s chances of running out of assets and savings during retirement increases greatly if they live longer.” The safe withdrawal rules of yesterday may no longer hold.

Second, the concept of retirement as a full stop must give way to retirement as a transition. If we live longer, it may no longer make sense to quit work entirely at 65. What if you phased into part-time work, shifted into different roles, or blended leisure and productive activity? The International Monetary Fund suggests that “70 is the new 50” in cognitive and physical ability for many older workers. Working longer doesn’t just boost income and savings; it changes the rhythm of retirement from plunge to glide.

Third, the cost structure of living longer must be factored. More years means more expenses. Health-related costs especially escalate. In South Africa, for example, as people age they use around three times more medicine and healthcare services. The positive flipside of longevity is opportunity; the negative is unrecognised risk.

From a savings and investment viewpoint the implications are major. You must save more. You must invest with a longer horizon (not just to retirement but well into the retirement phase). You must revisit your asset allocation to ensure it can sustain a longer draw-down period and guard against sequence-of-returns risk and inflation. As one analysis puts it: “If you knew you’d live another decade longer than expected, what would you change today?”

On the behavioural side, we must gain what could be called “longevity literacy” – the ability to ask the right questions: When might I really stop working? How many years will I live? How much do I need for those additional years?

Finally, the social and moral dimension: living longer offers more potential to contribute, to learn, to mentor, to engage in civic life. But that requires financial freedom. If your savings don’t stretch, additional years become years of constraint, not of possibility. In other words, the duty to plan for longevity is not about selfish prolongation – it is about preserving choice, dignity, and purpose for the decades ahead.