Founded in England in the 1860s, squash is an indoor racket sport for two people, played in 153 countries. They play inside a four-walled court with light metal rackets and a hollow rubber ball that frequently flies by at 150 mph. Starting with a serve, players play a “rally,” taking it in turns to hit the ball onto the front wall. The ball can rebound off the back and side walls — creating an infinite number of angles and shot possibilities — but is only allowed to bounce on the floor once between shots. Forbes Magazine rated squash number one in its survey of the World’s Healthiest Sports – a single rally can last 20 or 30 shots, and the lunging and sprinting requires high levels of speed, endurance and power. Players can burn more than 1,000 calories per hour – and they must use strategy, skill and mental endurance to outwit their opponent rather than sheer strength.