Why We Procrastinate

A huge problem of mine, to which I'm sure others can relate, is procrastination. A habit that did not start until I began high school, my procrastination has only grown worse with time. I always tell myself that I'm just being lazy, but that never seems to motivate any change or improvement. This article on procrastination, however, could prove useful in identifying what fuels this habit.
The article defines it as a "default habit" that we resort to whenever we face an uncomfortable situation (whether it is stress, anxiety, or the possibility of boredom that makes us hesitate from starting). Surprisingly enough, the article also cites self-help and self-development as causes of the habit. Delaying a change in healthy or good behavior is easier than initiating it only to encounter the possibility of failure.
Personally, I think I procrastinate because I feel intimidated or anxious about the task at hand and envision failure before even thinking of how I would approach it. In a sense, this "default habit" reminds me of the defense mechanisms we learned about in class, especially displacement. Instead of facing something uncomfortable, we shift our focus to something different and more comfortable. But when and why does this default habit begin or develop? If it can be considered a defense mechanism, are our comfort zones the threat? Or are we?