For a large task, allocate small amounts of time daily to remedy it. Shorten phone calls and deal with trivial things once a week. If possible, have someone else answer your phone if you are busy. Avoid clutter in your life. Organize your desk and room.
Clutter tends to hinder concentration and can create tension and frustration.
Try to focus all of your attention on one task at a time. It will help you to get things done. Never write when you can call, and never call when you can speak face to face. Get things over with as soon as possible to save time. Be on time for meetings.