Gelassenheit is a German word without exact translation. Humility + yielding + calmness + surrender of one's will to God and community.
In Practice
Don't stand out (identical clothing). Don't be proud (no photos, no mirrors, no boasting). Don't insist on your way (community decides, you comply). Don't pursue success for its own sake (money = means, not goal). Accept suffering (God gave it — God knows why).
Contrast with Modernity
The world says: be yourself, stand out, pursue success, express yourself. Amish say: be part of the whole, don't stand out, serve others, surrender pride. Two opposite views on life's meaning.
Why It Works
Depression among Amish is 5x lower than Americans. Suicide 10x rarer. Self-expression creates anxiety (what if I'm not unique enough?). Gelassenheit removes anxiety (my place is defined, I'm part of a whole).
Criticism
Suppression of individuality? Perhaps. But Amish see individuality differently: not 'who am I?' but 'what do I do for others?' Define yourself through contribution, not consumption.