Worry or Think Time
Set aside a specific time each day to think about the things that keep entering your mind and interfering with your concentration. For example, set 4:30 to 5 p.m. as your worry/think time. When your mind is side-tracked into worrying during the day, remind yourself that you have a special time for worrying. Then, let the thought go for the present, and return your focus to your immediate activity.