This is the question that John Pitlick discuses in his article at http://www.johnpitlick.com/personal-development/self-growth/mental-weight-causes-procrastination.
Does the mental anguish caused by not completing things cause you to not enjoy yourself? In the article he explains:
“… let me tell you about a dangerous side effect of procrastination. I call it ‘mental weight’. ‘Mental weight’ is the weight you feel on your brain for having a whole lot of things left unfinished that you need to do but are procrastinating on.
An example is