It's not only the fact that adventurous activities are fun and burn a whole lot of calories, more than any gym session you can mention they have loads of other health benefits.
You see being outside and getting sun on your skin, fresh air in your lunges is better than any drug the doctor can prescribe for you. Having a healthy adventure hobby will make you feel great, give you a reason to get out into the country and help you live a long healthy life.
Try my mountain bike skills days
Glenn (Adventure go to guy) Hill