Grab a few dirt bikes and hit the trails up up up the mountainside. Want to talk about fun, try a 4 wheeler and just slide around the corners jumping over bumps and dodging trees. Going up the mountainside is one thing but going down it is a whole other story, It's very easy to slide into a tree (yes I have done that a few times...well....okay so more than a few times but hey whos counting right). I know some people who would rather take a mountain bike and just get some great exercise and I have seen them ride up some really steep hills that some people can't even walk up!
For all other people just kicking back camping watching the trees sway back and forth against the dotted star sky is a great way to spend time with nature. Maybe have a campfire roasting some marshmallows listening to the campfire crackle while giving out strange shadows against the tree lines around you. Thats memory making and you will relfect, masure and live but that few days camping for the years to come until you make more new memories like it.