PGA golfing great Tom Watson has said that he liked to picture legend Sam Snead's swing when the heat was on.
The same can be said for whatever sport you play. When the pressure is on, visualize an athlete that excels under pressure, and picture his/her success in your mind.
When you get nervous or jittery, think about this technique to calm you down and get you relaxed. Regardless of what routine you use, do so with a positive mindset that produces positive results. Sometimes, seeing is believing!