Strength and flexibility are a must for golf as they are, of course, for every other sport. You'll particularly want to strengthen your wrists. Strong wrists guarantee more efficient play. Ideally, your left and right wrists should be of equal strength. Flexing (squeezing) a soft ball will help strengthen your wrist muscles and makes a good pre-round exercise.

Try upper body stretches and swings without the club to help strengthen your swing action and develop "muscle memory:" that is, using the correct movements of the swing instinctually. Before you play a round of golf, cross your arms in front of you in the "cross your heart" position (right hand on left shoulder, left hand on right shoulder) and practice the full golf swing "with no arms."

Loosen the muscles in your lower back and stretch your spine before hitting your first ball of the day. This will help avoid instant swing stiffness as well as long-term back trouble, the most common golf-related injury.

Here's a wonderful exercise for swing rotation, courtesy of Christine "CC" Cunningham, M.S., writing in Personal Trainer Magazine:

Stand with your feet shoulder width apart and knees slightly bent. Keeping the lower body still and the hips forward, reach down with the right arm toward the left foot. Then reach up and rotate your trunk to the right. (Do not rotateyour hips). Try to bring the left shoulder to the forward position. Raise the right arm up, bend the elbow to 90 degrees, and externally rotate it. Reach back down and repeat, then perform the exercise with the left arm. Emphasize rotation at the trunk without moving the position of the lower body.