Check out the new edition of 15-30 Tennis Digital Magazine. There is a great article on NBA point guard Steve Nash about growing up playing multiple sports. There are many parallels between tennis and basketball, especially for the point guard position. Andy Roddick and Mardy Fish played high school basketball together. Nash talks about the the physical similarities, in athleticism, mobility, strength and flexibility, and also the mental toughness required for both. He is one of the most creative players in the league, and discusses the similarities in creativity, vision, and ability to find angles.
Also featured is an article by Allen Fox. Fox played at UCLA and coached at Pepperdine, and has wrote multiple books including two that are very good: Think to Win and Tennis: Winning the Mental Match. The article talks about approaching every point with maximum focus, as you don't which points turn out to be the biggest points. The average margin of victory in a close set is 4 points.