Sometimes it appears that we learn the art of being sick to excuse our apathy and fatigue. It becomes a tool to avoid unpleasant tasks and responsibility. Don't underestimate the ability of your mind to cause aches and pains. I found out that the stress of making the trip often cured me of my minor aches and pains. However, if I had made the trip in the spirit of antagonism, my faulty reaction might have put me in hospital for a week.
Depression takes a high toll in personal productivity.
Many gifted people never achieve their potential because of depression induced apathy. Gloom and pessimism produce apathy and fatigue which induce aches and pains which reduces our productivity, which gets us fired, which puts us in the poor house, which makes us irritable which causes us to withdraw which makes us more depressed and the spiral deepens. Remember, this is the high cost of acting like Jonah and reaching down into your jeans and paying the fare to run away from God given responsibilities. Jonah chapter four opens with a picture of an angry, depressed man sitting in the desert sucking his thumb. He's angry at God.