Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal.

[Viele sind hartnäckig in Bezug auf den einmal eingeschlagenen Weg, Wenige in Bezug auf das Ziel.]

Friedrich Nietzsche (1844-1900) German philosopher and poet

Human, All Too Human [Menschliches, Allzummenschliches], Part 1, ch. 9 “Man Alone with Himself [Der Mensch mit sich allein],” ¶ 494 (1878)
    (Source)

This is a frequent translation of this passage, but I cannot find the original translator.

(Source (German)). Alternate translations:

Many are obstinate with regard to the once-chosen path, few with regard to the goal.
[tr. Zimmern (1909)]

Many people are obstinate about the path once it is taken, few people about the destination.
(tr. Faber/Lehmann (1984)]

Many are obstinate with regard to the path once they have entered upon it, few with regard to the goal.
[tr. Hollingdale (1986)]