In chess, knowledge is a very transient thing. It changes so fast that even a single mouse-slip sometimes changes the evaluation.
I have a love for astronomy; Aruna, my wife, and I love travelling, so whenever we get an opportunity, we set off to explore places that have tickled our interest. We are also wildlife enthusiasts.
I go to the gym every day. That tends to taper off when I'm at a tournament. During tournaments, I'm not trying to build fitness. I'm simply trying to keep away any kind of tension. I go for long walks to clear my head.
Before a game, I avoid having a heavy meal so that I don't feel sleepy at the board. You eat to be healthy, and that generally takes care of everything. Also, you can't be too finicky, since at tournaments you tend to eat at restaurants here and there. But, as long as you're eating sensibly, it's all good.
There are two aspects to being competitive; one is to do with sports, and the other is about technical skills. Being able to recollect the moves and apply them when necessary is a critical aspect.
Preparedness for a game that usually lasts four-five hours requires good physical condition and also steady nerves.
