I'm 14, 5' 10", and around 160 lbs. The fastest serve i've ever hit was around 85 mph. I know how helpful a serving video is but i cant really upload one right now. I'll try later. But how do people serve 100mph? I find it impossible! I've tried hitting harder, supinaiton, knee bend, body rotation, jumping in more but all that happens is me losing my balance and swinging and missing and the ball falling on my head. What do I do to get it up to that speed? Anyone else experienced the same problem?