Physical exercise guru David McGuire is always cheerful, even though he gets up at 4 o'clock every morning. But don't let that put you off. He's the best fitness instructor around. A former ballet dancer with a background in competitive gymnastics, McGuire isn't the typical barrel-chested gym brute so often found hanging around a set of dumbbells. He often incorporates yoga, Pilates, and dance steps into his workouts, alongside the usual weight lifting, balance, and core strength exercises. So you leave his sessions exhausted but somehow also in a Zenlike state. In addition to putting clients through their paces on a one-on-one basis, McGuire also runs popular morning boot camps throughout the year with the help of a carefully culled team of assistant trainers. McGuire's bracing if barbaric daily blend of squats, push-ups, and crunches at various locations in the Marina and Crissy Field (no gym for him!) is great for anyone silly enough to get out of bed at around the same time that he does.