When you establish a routine, the difficult becomes routine. Chauncey Billups, a Detroit Pistons point guard, describes his formula for nailing two free throws to tie a game in the fourth quarter: "I know it's a big shot, but I don't even think about the moment. If I put more pressure on it, then it becomes a mental thing. I treat it the same as a free throw in the first quarter by doing the same routine every single time. I focus on the rim. I take four dribbles, spin the ball, and get up under it. My routine puts me into a calm state. It's just me and the rim."
Part of training is mentally training yourself as well. When your training physically you also have to train your mind. Focus on what your task is, every time you go to work out have a mission for what you are going to do that day and when you friend says something that irks you, take a deep breath through your stomach and hold it then release.. If it doeant work the first couple times thats because its a skill you have to practice.. so if your focused during your work out then you will do a better job and feel better, remember to go to the gym with a mission.
hope this helped:)