Yesterday I went to Kelso Conservation Area in Milton (http://www.conservationhalton.on.ca/kelso.html) for a bit of biking.
It has been years since I rode a mountainbike, so you can imagine how tired I was after 2 and a half hours of riding up and down the hill, jumping over rocks and fallen trees. There were some other, more x-treem, trails, but I did not dare to try them. Maybe next time.
The only side effect of this little adventure is that my *ss is hurting like hell.