Determine to have extraordinary master level concentration when you bowl. Remember that concentration is not holding your mind on one thing. It is directing your attention within a determined sphere of things. Thus… choose 3 to 5 to 7 things you wish to have your attention on when you bowl.
You can write them on a list and keep them in your pocket if you wish. Practice bowling for longer and longer periods of time with your attention moving from one of those things on your list to another.
You can condition your consciousness to remain within a predetermined set of criteria. This is the true secret to concentration. Don’t make the mistake of trying to hold your mind in one place. It is not possible. The mind’s tendency is to move. Control the movement within the sphere (list) of things you choose!
When you notice your mind has wondered from your predetermined list of things, gently and uneventfully bring it back to one of the things on your list and simply put it back into motion on the list. The key here is GENTLY and UNEVENTFULLY.
Practice this, and before long, if they are not already doing so, people will comment on your extraordinary level of concentration. Guaranteed!