Being able to run fast on the tennis court is helpful, but many of us are never going to be able to "run fast".
Paying more attention to reacting quickly to the direction that your opponent has just hit the ball, will help give you a better chance to get there and have a good swing at it. Try watching the ball all the way from your point of contact until the ball is hitting the strings and coming off of your opponent's racquet. Your first thought should be "will I have to hit a forehand or a backhand?"
Once you identify the answer, turn your shoulders and start the racquet back. Next, get your feet moving in the direction that the ball has been hit. Very often our instincts are to start running to the ball rather than using the shoulder turn to help get the racquet moving. This makes your preparation less efficient and can put you in a position of not being able to take a normal swing once you get to the ball.
By identifying the direction of the ball early, everything will become more coordinated and smooth. Keep reminding yourself to watch your opponent's contact of the ball with intent of identifying the direction of their shot. This will give you a head start in your preparation to hit the shot, and help you hit the ball with a more normal swing once you get there.
Steve Annacone, USPTA Elite Pro, is the Director of Annacone Tennis, www.annaconetennis.com and MyHamptonsPro, www.myhamptonspro.com throughout the Hamptons, NY. In addition, Steve and Miguel Coelho have introduced the JET (Junior Elite Tennis) program at the Tucson Jewish Community Center (Tucson, AZ) for high level players ages 8-18. Please contact Steve at email@example.com.