Also, it's good to practice throwing a football at about a 45 degree angle
(this also happens to maximize the distance of the throw), since the
serve is hit "up." I used to play football when I was little and I think this
helped my serve. When I was 5'3" and 120lbs, my coach radared my serve
and it was 10x mph. Pretty sure it would have been weaker without football.
At the time, I think I could throw a football about 45 yards. There was another
guy on the tennis team that could throw 70+, but his serve wasn't super hard
b/c he roided up too much over the summer and got too 'uge.
http://goo.gl/NPBIWt (How to serve like Sampras)
http://goo.gl/KZfDaJ (Star Wars superfan battle)