Something that I tell my students is that their only job is to find the next move and that anything else (results, rating, prizes etc) is a distraction. I particularly like this because of its parallels in the meditative arts and the monkey mind which seeks to distract you.
There are also external distractions such as noisy playing environments and opponents who want to win by non chess means. In such cases I can recommend ear plugs or even ear defenders for the hypersensitive, plus a reasonable degree of assertiveness to complain to your opponent and/or the arbiter.
Before I took up tai chi I had a much greater need of ear plugs and in a way they might have helped me get the Grandmaster title. In Gausdal in 1993 I was wearing them in my game against Yuri Razuvaev and wasn’t sure whether or not he had offered a draw. As it would have been unseemly to clarify (“Did you just offer me a draw?”) I kept on playing and won. And this was an important stepping stone on the way to another norm.