“Difficulties are meant to rouse, not discourage. The human spirit is to grow strong by conflict.” — William Ellery Channing · Self-Culture, 1838
“Do not pray for easy lives. Pray to be stronger men.” — John F. Kennedy · Address to the National Prayer Breakfast, 1963
“You are never strong enough that you don't need help.” — César Chávez · widely attributed, labor movement speeches
“It always seems impossible until it's done.” — Nelson Mandela · widely attributed, various speeches post-1990
“The man who moves a mountain begins by carrying away small stones.” — Confucius · attributed to Confucius, various collections