It would much conduce to the settlement of your heart, to consider that by fretting and discontent you do yourself more injury than all your afflictions could do. Your own discontent is that which arms your troubles with a sting; you make your burden heavy by struggling under it. Did you but lie quietly under the hand of God, your condition would be much more easy than it is. “Impatience in the sick occasions severity in the physician.” This makes God afflict the more, as a father a stubborn child that receives not correction. Beside, it unfits the soul to pray over its troubles, or receive the sense of that good which God intends by them. Affliction is a pill, which, being wrapt up in patience and quiet submission, may be easily swallowed; but discontent chews the pill, and so embitters the soul. God throws away some comfort which he saw would hurt you, and you will throw away your peace after it; he shoots an arrow which sticks in your clothes, and was never intended to hurt, but only to drive you from sin, and you will thrust it deeper, to the piercing of your very heart, by despondency and discontent.
From John Flavel’s fantastic book, Keeping the Heart