Feelings of well-being increase in the seventh decade of life, the longest-running study following the progress of people from birth has shown.
Researchers who quizzed more than 3,000 participants found that approaching 70 can put a spring in your step.
Aged 60 to 64, the volunteers were tested on a range of mental well-being measures including feeling cheerful, confident, optimistic, useful and relaxed.
When they were asked the same questions again at age 69, there was an improvement in all 14 categories that made up the well-being scale.
This was despite most of the group experiencing at least one chronic disease including arthritis, diabetes and high blood pressure.
Dr Mai Stafford, from the Medical Research Council Unit for Lifelong Health and Ageing (LHA) at University College London, said: "What we've found is that, on average, levels of well-being increased during people's sixties.
"We found that one in five experienced a substantial increase in well-being in later life, although we also found a smaller group who experienced a substantial decline."
The MRC's National Survey for Health and Development (NSHD) was launched in March 1946 when thousands of newly-born babies were recruited into the study.
One of its aims is to look at how individuals change over time in order to pinpoint common experiences that make us happy.
Two 70th birthday parties for study participants are planned in London on Tuesday and Manchester on Thursday.