Every city has its "central park" -- the one in the middle of everything where you can hike, bike or just sit in the grass next to a babbling brook and forget that you live in an urban jungle. Well, our babbling brook is Buffalo Bayou, and while it's not the prettiest body of water in the world, it provides an excellent centerpiece for the endless loop that is one of the finest low-stress hike/bike trails in any urban area. Luckily for the fitness-minded, Houston is not really an outdoorsy kind of town: Most people drive their SUVs to the gym, so the trails are generally empty even at peak times. For those who dare to step outside the comfort of climate control, that makes the winding, multi-terrain journey from downtown to Shepherd and back quite a joy. Stop off at any one of the exercise stations for a little extra workout, then hop back on your bike and lose yourself in the trees.