In with the good air, out with the bad. Breathe. Deeply. Let the fresh sea air fill your lungs. You'll soon need every molecule of it. Standing at Boca's South Beach Park pavilion on Palmetto Park Road and A1A, while looking out over the beautiful waves breaking upon the shore, do all of your muscle stretches. Once you're warmed up, start jogging along the wide, gray concrete A1A jogging trail, which runs north about six scenic miles. You'll pass tall, luxurious condominiums, spacious city parks and public beaches, wild vegetation preserves, exotic gargantuan mansions, and even a handful of snowbirds in cars, who seem to drive way too slow. Traffic is far from menacing here; a four-foot-wide swale separates the trail and the road for most of the distance. When the right moment comes (if your chest is aching, you've gone too far), turn around and jog back. Upon your return to your starting point, quench your thirst with a sports drink at the convenience store conveniently located on the corner of Palmetto Park Road and A1A. Hey, if this jog doesn't pump you up, nothing can.