Abs of steel? We prefer a more natural look: abs of granite. We sculpt them at the Phoenician, where the glitzy Centre for Well-Being spa goes back to basics with its new "Nature's Gym" outdoor obstacle course. Starting at the base of Camelback Mountain, the all-natural workout finds fitness equipment in the desert's natural resources. Resort instructors lead 75-minute cross-training sessions, including stretches on desert boulders, pull-ups on paloverde trees, bicep curls with granite rocks, sit-ups on golf tee boxes and yoga exercises in flower beds. And packing a cardio punch: power walks on the golf course and stair-stepping through flowered paths. It all ends with cool-down stretches amid garden waterfalls and -- in our own restorative touch -- three vodka tonics poolside.