On the load a reason will carry
“He who has a why to live for can bear almost any how.”
Almost is doing quiet work in this sentence. Nietzsche is not claiming that meaning makes suffering acceptable, only that it makes suffering carryable, which is a lower and more honest claim.
The uncomfortable corollary is the one people skip: a why that is borrowed, or inherited, or never examined will hold weight exactly as long as it is believed. Some of them fail under load, and they fail at the worst moment.