This hatred of other people's success, combined with despair about your own life, creates a mind that's angry at fate. You start complaining constantly about the times you live in. You retreat into isolation and brood over how miserable you are, until you become sick of yourself. The human mind naturally wants to move and stay active. It loves any chance to get excited and forget about itself. The worse someone's character is, the more they crave this kind of distraction. They want to exhaust themselves with frantic activity, like how infected wounds crave the very hands that hurt them, or how a rash enjoys being scratched.
This dislike of other men's progress and despair of one's own produces a mind angered against fortune, addicted to complaining of the age in which it lives, to retiring into corners and brooding over its misery, until it becomes sick and weary of itself: for the human mind is naturally nimble and apt at movement: it delights in every opportunity of excitement and forgetfulness of itself, and the worse a man's disposition the more he delights in this, because he likes to wear himself out with busy action, just as some sores long for the hands that injure them and delight in being touched, and the foul itch enjoys anything that scratches it.