If you're a hiker, there are hills here for some decent elevation change (not bad for the Midwest). There are many trails which you can combine to get a good amount of miles in.

The camping here is always good. The sites are not huge, but not too tight and are pretty well spread out. The lodge is at the top of the hill with a nice little giftshop and restaurant as well as cute, quaint cabins for an overnight stay.