The unfortunate corrolary to this is that if you are fueling your tasks with anger and caffeine, letting go of that anger can be supremely demotivating. Trying to be a healthier person to be around can turn around and sap your will for your efforts. At least that is how my experience has been.
Maybe the upgrade to this can be righteous anger, like an anime hero, lots of screaming and yelling but it's out of raw determination rather than hatred for all things lol.