Improving your happiness in retirement can be achieved by doing one thing – that’s not having started saving earlier and more often (though this could relieve stress once retired, which might ultimately help you achieve this one thing). Instead, this key to retirement happiness is actually staying healthy. Indeed, in a study by researchers from The American College, Eastern New Mexico University and Texas Tech, retirees who reported they were in good, very good, or excellent health were more likely to feel satisfied with their retirement than those with poor or even fair health. What’s more, health status was even more likely to lead to retirement satisfaction than good relationships or leisure spending.

Other research bears out just how much good health is linked to retirement happiness. According to a recent Nationwide Retirement Institute survey, a third of recent retirees say that health problems are interfering with their retirement.

Of course, you don’t have absolute control over your health. But there are a number of things you can do to reduce the chance that an illness or other physical problems will cast a pall on your post-career life, including staying active and exercising regularly, getting regular checkups, and receiving proper treatment for any ongoing health issues.

Aside from enhancing your enjoyment of retirement in general, looking after your physical well-being may also help you feel more financially secure by possibly lowering the amount of money you’ll have to shell out for health care, which is one of retirees’ largest expenses.