On a high performance windsurfing board trimmed out for max speed, you're skimming the surface while hanging on for dear life. Just like everything else, the adrenaline coursing through the body can be quite addictive.
Trying to predict the behavior of winds dancing across the water in front of you is a real challenge but pays off when you anticipate its strength and direction correctly. This is especially important when you're windsurfing -- it's just you against Mother Nature and often times, you'll get slam when the winds are unpredictable with gusts of wind sneaking up behind you. When strong winds become really gusty, you need to let out some of the sail and lean back for more counter balance.
The windsurfer is fitted with a "diaper" with a metal hook attached to harness straps, which are then attached to the boom. This is where the balancing act gets kind of hairy. Both feet are secured into foot straps to prevent from launching yourself from the board. I'm strictly a flat water windsurfer, trying not to get airborne as much as possible.
One time while windsurfing in the Gorge (part of Columbian River), I nearly drowned by rigging up a larger sail than the rest of the fleet. I got slammed repeatedly, drifting down river in that cold and fast current. I finally touched ground, carrying the whole rig on my head, as I struggled back to my warm Jeep, about half a mile up stream. Thank god for Kaluia and coffee and quickly passed out for the rest of the day. Here is a video of a windsurfer racing a high performance trimaran.