What everyone has been saying so far is pretty much all true. A few things i found that worked for me:
1. I kept something in my pocket to fiddle with. Whether it be beads, my leatherman, a nut, or whatever, i helped me calm my nerves because i could take it out and play with it which distracted me.
2. Don't watch the matches of teams you are worried about. This is especially true in elims where having a clear head is extremely important. I learned that if i watched matches of teams with better robots, or of people we were about to play against, i would psyche myself out and it would throw me off my game.
3. Water = winner. Whether or not you want to believe it, doing even the most trivial tasks such as drinking will distract you and you will feel better.
4. Take a walk outside! I know this sounds extreme because most of us are afraid of the sun, but fresh air will help you think better and more clearly. I remember distinctly last year at MAR championship we lost either 3 or 4 matches in a row where we scored just about as many points as we could have, including a match where we scored 105 points by ourself and still lost. I was really upset and stressed because i thought everyone would be angry at us for losing but then i went for a walk outside and calmed down. We played well the next match and won and everything got better.
Point being if you ever feel too stressed out, kick back for a bit, go outside, take a deep breathe, and just chill. Good luck!
