Further, a little self-control at the right moment may prevent much subsequent compulsion at the hands of others.

[Daß jedoch ein kleiner, an der rechten Stelle angebrachter Selbstzwang nachmals vielem Zwange von außen vorbeugt.]

Arthur Schopenhauer (1788-1860) German philosopher

Parerga and Paralipomena, Vol. 1, “Aphorisms on the Wisdom of Life [Aphorismen zur Lebensweisheit],” ch. 5 “Counsels and Maxims [Paränesen und Maximen],” § 2.15 (1851) [tr. Saunders (1890)]
    (Source)

Source (German). Alternate translation:

Nevertheless, a little self-restraint applied at the right place afterwards prevents much restraint from without.
[tr. Payne (1974), 2.15]