Just something I taught myself in the Army, get mad at the target and focus hard on the front sight. It's hard to get mad at a paper target but you can psych yourself into it. Being so mad at a target you want to kill it focuses the mind and you can't worry about your problems on the range so you don't do them.
You can imagine you're hunting and think of the round paper target as a trophy buck. You want that sucker so badly you're not going to let him pull any tricks and you want to damned certain drill a hole through him. Make the X ring a patch of hair dead center in the kill zone, focus on the front sight as if your life depends on it and bag that buck.
As a middle age man I decided to play lacrosse with the university club. I wasn't very good. One night there was meditative space music on the radio. I got up, put my gloves on, took my stick and closed my eyes and imagined being on the field so intensively I could have actually been there. Moving to the rhythm of the music I saw in my mind balls coming at me every which way. I worked my actual stick in sync with my imaginary stick, doing every thing perfectly. I spent an hour dancing this way. The next day I was working the ball as well as anyone.
What you do wrong is all in your mind. Doing things right is all in your mind. Go to a dark room with your rifle, close your eyes and imagin a 360 degree firing line around you, begin dancing with your rifle, popping targets in a random sequence imagining putting balls through the X rings. Only imagine doing things perfectly right. Don't get self conscious and let worry over technique enter your mind. Don't let anyone watch so you might think yourself a fool and break your rock solid concentration.
The mind can train you, or it can defeat you. Use the positive part of it to bash the negative. Let the mind that doesn't flinch subdue the mind that does.
Now I need to practice what I preach.