The hell to be endured hereafter, of which theology tells, is no worse than the hell we make for ourselves in this world by habitually fashioning our characters in the wrong way. Could the young but realize how soon they will become mere walking bundles of habits, they would give more heed to their conduct while in the plastic state. We are spinning our own fates, good or evil. Every smallest stroke of virtue or of vice leaves its never so little scar.

William James (1842-1910) American psychologist and philosopher

The Principles of Psychology, Vol. 1, ch. 4 “Habit” (1890)
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This chapter originally published in Popular Science Monthly (Feb 1887).