Some joggers are slaves to routine. They run the same course week in, week out, until the pavement around their neighborhoods bears the imprint of their New Balances. But for those looking for a break from the smooth-paved paths of their local park, consider Ballwin's Castlewood State Park. Perched on the Meramec River, Castlewood offers a series of rugged trails that provide a scenic, tree-shaded break from the monotony of city running. The trails at Castlewood can be a little rugged at places, so you'll have to watch your step, but it's worth the risk for views of the river and the chance to work your quads on some of the steeper inclines.