I simply can't resist a full reply.
Chess is not a sport because there is no skill in the physical execution of the moves.
By that I mean, if I want to move rook to e1 I just pick it up and move it to e1. I can do that repeatedly with 100% precision. Every time. You can do it with a mouse. If you're playing blindfolded you can even do it just by saying the words: "Rook to e1".
Contrast that with tennis. I can't just think "medium paced serve into the top left corner" and have the execution of that move go perfectly every time.
The tactics and strategy of chess and tennis certainly require plenty of skill, but the difference is in the execution of the basic moves.
It's actually one of the things I love about chess.
Once the mechanics of playing the perfect forehand or swinging the perfect nine-iron chip shot are out of the equation, the game is entirely about tactics and strategy.
Incidentally, this was the same argument I had with a friend about whether motor racing was a sport. At first my reaction was no, but then when argued that there was a great deal of skill in the physical execution of the moves, I had to concede.
So motor racing is a sport. Chess is not.
If the amount of sweating was the only criteria to classify it as a sport, I can assure you that based on my own experience, chess would definitely qualify.