Climb a mountain
Climb with the challenger a mountain, you chose witch one
the best views
Climbing is a fantastic exercise, you can do it while you enjoy the nature and the fresh air, once you start going to the mountains, you will never want to stop.
You don't need to climb the Everest, chose a mountain that it is a challenge, but possible to climb. Prepare yourself and bring with you all the necessary stuff, winter clothes, food, water and other things that can help you in emergencies.