Using your non-dominant arm is crucial when preparing to hit a forehand. Not only does it help with your upper-body unit turn, releasing the non-dominant arm prior to contact helps generate spin and power. Jim Mclennan breaks down this simple trick that will surely help your forehand in this One Minute Clinic. 

From Rafael Nadal to Roger Federer, and everyone in between, it's imperative that you use your non-dominant arm to turn your shoulders, as well as judge the distance of the tennis ball from your body in order to create proper spacing.