YOKOTA AIR BASE, Japan -- Water fitness instructor, Mikito Kurihara, demonstrates a simple arm and lower back stretch during a water aerobics class at Yokota Air Base, Japan, July 12, 2011. Swimming and water aerobics are a good way for people to exercise, especially those who can't necessarily do physical training exercises on land. (U.S. Air Force photo/Airman 1st Class Katrina R. Menchaca)