“Consider it pure joy, my brothers, whenever you face trials of many kinds, because you know that the testing of your faith develops perseverance.”

I like the way Orison S. Marden puts flesh to this verse with some practical applications in his chapter “Useful obstacles”. –

“Will he not make a great painter?” was asked in regard to an artist fresh from his Italian tour. “No, never,” replied Northcote, “Why not?” “Because he has an income of six thousand pounds a year.” In the sunshine of wealth a man is, as a rule, warped too much to become an artist of high merit. He should have some great thwarting difficulty to struggle against. A drenching shower of adversity would straighten his fibers out again.
The best tools receive their temper from fire, their edge from grinding; the noblest characters are developed in a similar way. The harder the diamond, the more brilliant the luster, and the greater the friction necessary to bring it out.
Only its own dust is hard enough to make this most precious stone reveal its full beauty.
The spark in the flint would sleep forever but for friction; the fire in man would never blaze but for antagonism.
From an aimless, idle, and useless brain, emergencies often call out powers and virtues unknown and unsuspected. How often we see a young man develop astounding ability and energy after the death of a parent, or the loss of fortune, or after some other calamity has knocked the props and crutches from under him.
The prison has roused the slumbering fire in many a noble mind. “Robinson Crusoe” was written in prison. The “Pilgrims Progress” appeared in Bedford Jail, Sir Walter Raleigh wrote “The History of the World” during his imprisonment of thirteen years. Luther translated the Bible while confined in the Castle of Wartburg. For twenty years Dante worked in exile, and even under sentence of death.