Have a plan.
When your mind is clear, set up a pre-shot routine, then follow it. It's okay to think of other stuff when you bowl. It's not a good habit to think of that stuff on the way to the line :-)
I always get up to bowl while the person I follow is still bowling. I do this to give myself time to inspect my ball for debris from the pin-deck or damage from flat head screws that may have become raised by vibration. I also check my flare rings and take the time to wipes
my ball if I need to.
When it's my turn, I'm ready to go. Fingers first, thumb and then position my feet. While looking at my target, I relax my arm as much as possible. I flex my wrist to remove any tension.
I want my ball to go back just after I start my second step, so I pay attention early. I like to feel the height of my back-swing and use that moment to also check my hand position at the top to make sure it's correct.
As the ball comes forward I fight-off any tendencies I may have to throw the ball and wait for it to reach the bottom before I do any thing. As my slide ends, the last thing I do is feel that I'm creating the right amount of leverage. For that my elbow must still be inside and my thumb and fingers go through the ball inside out.
At the end, I do a quick check of my finish position and where I ended up at the line.
All of this probably takes 5 seconds. No time to think about work or anything else :-)
I know others who almost retire during their pre-shot. I think the longer you spend in your pre-shot the more likely you will make a mistake.
In competition, having something to think about, is a good thing. When its your turn to bowl, have nothing but bowling to think about. Have a routine and follow it. The more little parts you can feel in the 5 seconds it takes to bowl the better.
Even when you practice, go through your entire pre-shot. Take a little extra time between shots. Don't get into aerobic bowling. Bowling too quickly when your by yourself can lead to bad habits and a feel you will never duplicate in league or tournaments.