Worry over producing the perfect project prevents them from finishing on time. Feelings of inadequacy can also cause delays. Fear of discomfort is another way of putting a stop to what needs to be done. Our behavioral patterns are the second cause. Getting started on an unpleasant or difficult task may seem impossible.
Procrastination is likened to the physics concept of inertia - a mass at rest tends to stay at rest.
Greater forces are required to start change than to sustain change. Another way of viewing it is that avoiding tasks reinforces procrastination which makes it harder to get things going. A person may be stuck, too, not by the lack of desire, but by not knowing what to do. Here are some things to break the habit. Those old excuses really don't hold up to rational inspection.