David D. Burns is an adjunct professor emeritus in the Department of Psychiatry and Behavioral Sciences at the Stanford University School of Medicine and the author of the best-selling book Feeling Good: The New Mood Therapy. Burns popularized cognitive behavioral therapy when his book became a best seller during the 1980s.
It can be helpful simply to make a written or mental list of the things you do each day. Then give yourself a mental credit for each of them, however small. This will help you focus on what you have done instead of what you haven't gotten around to do. It may sound simplistic, but it works.