A doctor may know more than a peasant, but a peasant and a doctor know more together.
Exercise, from a public health perspective, is an unmitigated failure. The world's longest-lived people live in environments that nudge them into more movement. They don't use power tools, they do their own yard work, they grow a garden.
You have to know why you get up every morning.
Walking is the only way proven to stave off cognitive decline - it works.
Serve yourself, put the food away, then eat.
Inconvenience yourself: ditch the remote, the garage door opener, the leaf-blower; buy a bike, broom, rake, and snow shovel.