Get your butt outside and go exploring. Ride a bike. Go fishing. If you're waiting for an Activities Director to make up your entertainment schedule, you're going to be waiting for a long time. Check your library for activity guides for your area. Or, check the visitor's info facility, if your area has one, for recommended activities in the area.
Nothing to do in the area outside? Volunteer yourself for community activities. Keep an elderly person company, volunteer as a co-coach in some kid sport. Deliver food to the needy from the local food bank.
Take up a hobby that needs some fine motor skills to challenge yourself. Or, pass the time building models, carving wood, fixing furniture, etc, etc.
You're a grown-up. Get off your butt and find something to amuse yourself.