Take a map and a compass along and learn to explore off the beaten path. Find old cellar holes, or new fishing spots. Or walk around an orienteering course.
Some people try to get around an orienteering course as quickly as they can.
It's a fun and challenging sport that requires using your head as well as your legs. Whether you walk or run, it's a way of keeping fit without a struggle. An activity you can still do as you get older. And it's for youngsters too, with their families, in groups or on their own.