Pain is inevitable, but misery is optional.

Tim Hansel

When you lose, do not lose the lesson

Dalai Lama

Nature, when she adds difficulties, adds brains.

Emerson

Difficulties strengthen the mind, as well as labor does the body

Seneca

Aromatic plants bestow
No spicy fragrance where they grow;
But crushed and trodden to the ground,
Diffuse their balmy sweets around

Goldsmith

There is healing in the bitter cup.

Southey