I recently returned to the UK after more than a decade of living away. So much had changed, but my local coffee shop was just as I had left it. The same assorted chairs – functional, comfortable and everything in between – the same branded wall decor, even the same management-approved muzak piped around the store. The one thing that had changed, however, was the clientele. At one time, this cafe used to be teeming with energetic teenagers and 20-somethings. Now, it was filled with reflective senior citizens and it seemed apparent: the world is ageing. Since the mid-1970s, the percentage of the world’s population over 60 has been increasing decade by decade. Advances in health care, hygiene, nutrition and lifestyle mean that more of us live longer. Add to this the global decline in birth rates, and we now have proportionally more older adults in society. Economists call this phenomenon "population ageing", while others talk about the “silver tsunami”. The World Health Organisation reports that in 2015 the over-60s made up around 12 per cent of the global population. This figure is projected to almost double by 2050. In some highly developed nations, the proportion will be higher still, with the over 60 year olds making up more than a third of the population. In 1950, when the UN began reporting data, global life expectancy was 45.7 years. This figure increased year on year, reaching 72.6 years in 2019. A slight decline in global life expectancy was reported between 2019 and 2021 – the first decrease since UN records began, a dip widely attributed to the Covid-19 pandemic. However, there are also suggestions that we are rapidly approaching a point where global life expectancy will plateau. Today, global life expectancy stands at 72.9 years. Have we reached peak age? The Bible (Psalm 90) famously places the typical human lifespan between 70 and 80 years. The Quran elegantly alludes to a lifetime as “alf shahr” – 1000 months or 83.3 years. Furthermore, certain Judaic traditions suggest an upper limit to longevity, proposing a maximum human lifespan of 120 years. In keeping with this, we have very few verified cases of people living beyond the age of 120. The longest-lived person in recent documented history is Jeanne Louise Calment (1875-1997), who lived to be 122. Currently, however, there is speculation that we can raise the bar on human longevity, helping more people live well into their 100s and perhaps even their 200s. In his book <i>Ageless</i>, Andrew Steel, a computational biologist, argues that there are people alive today who will live to see their 150th birthdays. Whether any of us live long enough to celebrate our bicentennials, only time will tell. What is certain, though, is that our societies are ageing rapidly. This demographic transformation will have profound implications on health systems, the workforce, the economy and beyond. No doubt, the so-called silver tsunami will reshape our societies. Such anticipated changes are a primary driver behind the UN declaring 2021–2030 as "the decade of healthy ageing". Further to that, last year, the government of Saudi Arabia made news when it entered the field of longevity research. The kingdom prioritised longevity, committing $20 billion to research promoting longer and healthier lives, a concept termed “healthspan” rather than lifespan. This investment makes the Saudi government the world’s largest funder of longevity research. The Saudi investment and the UN's decade of healthy ageing is an acknowledgement that we need to do more to respond to the rights and needs of older people. A few of the decade's proposed challenges include creating age-friendly environments, ending ageism and offering appropriate and responsive health and social care tailored for the elderly. In short, the goal is to improve the lives of older people, their families and their communities. Population ageing is a global challenge, and promoting healthy ageing is a worldwide initiative. Enjoying good health in old age must also include mental health. According to the WHO, around one in five adults over 60 experience a mental health problem or neurological disorder. Depression and dementia are the most common problems; anxiety disorders also feature prominently. It is also notable that in the US, at least, the highest rates of suicide are among males over the age of 85, according to the Centres for Disease Control and Prevention. People over the age of 60 are at heightened risk for specific stressors known to affect mental health. For example, as we age, we are more likely to experience bereavement and the shrinking of social support networks, the loss of a spouse and lifelong friends. Similarly, ageing is associated with reduced mobility and health complaints. Additionally, retirement from the workforce can result in the loss of socioeconomic status, a daily routine and a sense of purpose. All these factors can precipitate loneliness, social isolation and mental health problems. If we increase the healthspan and hope to meaningfully contribute to the decade of healthy ageing, we cannot afford to ignore mental health. Unfortunately, in many nations, older adult mental health services are an afterthought, if they exist at all. Similarly, many public health initiatives that promote well-being focus on schools and workplaces. But what about those who have retired? The French Author Pierre-Jules Renard once wrote: “It is not a question of how old you are, but a question of how you are old.” With this in mind, it is especially important to promote the psychological well-being of the world's ageing population.