The suffering of sickness and the suffering of persecution have this in common: they are both intended by Satan for the destruction of our faith, and governed by God for the purifying of our faith... Christ sovereignly accomplishes His loving, purifying purpose, by overruling Satan's destructive attempts. Satan is always aiming to destroy our faith; but Christ magnifies His power in weakness.
John PiperSleep is a daily reminder from God that we are not God. Once a day God sends us to bed like patients with a sickness. The sickness is a chronic tendency to think we are in control and that our work is indispensable. To cure us of this disease God turns us into helpless sacks of sand once a day.
John Piper