Lest I made the most amazing sport In Ever sound unpleasant (or at least not worthwhile), I did come across this on Wikipedia:
Squash provides an excellent cardiovascular workout. In one hour of squash, a player may expend approximately 700 to 1000 calories (3,000 to 4,000 kJ) which is significantly more than most other sports and over 70% more than either general tennis or racquetball. The sport also provides a good upper and lower body workout by utilising both the legs to run around the court and the arms/torso to swing the racquet. In 2003, Forbes rated squash as the number one healthiest sport to play.
(Photo from "Squash's top photographer" Steve Line at the Tournament of Champions in Grand Central)