Often it’s a lot easier than you think.
You don’t need to analyse, or even think about, why you do it. That can all too easily become just another excuse for delay.
Research has shown that if you can just make a start on the task, and work at it for a few minutes, you will often feel an urge to see it through to completion.
This is known as the Zeigarnik Effect after early 20th century Russian psychologist, Zuma Zeigarnik, who first discovered that starting any activity causes your mind to experience a kind of psychic anxiety. Once the activity is completed your mind breathes an unconscious sigh of relief, and can move on to something else.
So, to borrow Nike’s famous phrase: Just Do It!
(This is my answer to a question asked on Quora)