“How wonderful to be alive,” he thought. “But why does it always hurt?”

Boris Pasternak (1890-1960) Russian poet, novelist, and literary translator

Doctor Zhivago [До́ктор Жива́го], Part 1, ch. 1 “The Five O’Clock Express,” sec. 4 [Nika] (1955) [tr. Hayward & Harari (1958), US ed.]
    (Source)

Alternate translations:

"How wonderful to be alive," he thought. "But why does it always have to be so painful?"
[tr. Hayward & Harari (1958), UK ed.]

"How good it is in this world!" he thought. "But why does it always come out so painful?"
[tr. Pevear & Volokhonsky (2010)]