The more uncomfortable you feel or the less confident you are over a shot or opponent, the more you become aware of your surroundings. As you learn to become more internal with your game and develop "burning focus" as they call it, the less these things will bother you. It just takes time and match experience, you can't just flick a switch or eat a different food before the match. It's all part of the mental game.
Some things that you can apply are, while sitting in your chair, watch the balls and never take your eyes off the table for anything. Don't look at the pretty girl across the room or hate on that banger scooping the cueball over in the corner. Stare at the rack until you feel like you're going to burn holes in the felt. This will keep you in the game even when you're parked in the electric chair.
Analyze your opponents patterns and anticipate the results. Try to figure out where your opponent will leave the cue ball if they should miss. This will give you more time to create a game plan when you finally get back to the table.
And don't forget, you can't control anything but your decisions.