Sow a thought, and you reap an act;
Sow an act, and you reap a habit;
Sow a habit, and you reap a character;
Sow a character, and you reap a destiny.
This is variously attributed.
John Stott quotes it without attribution in his The Message of Galatians, specifically in the chapter on Galatians 6: 6-10. In that scripture passage, Paul writes, "Whatever a man sows, that he will also reap," also without attribution. But the truth of sowing and reaping is often expressed in the Old Testament (e.g. Gen 8:22), and Paul, being an OT scholar, would of course have been familiar with the saying. He reminds the Galatians reader of a truth that was so embedded in the culture of Paul's time that even then it was an ancient epigram. The scripture passage has both specific and general applications of that truth to the churches at Galacia to whom Paul was writing and to the Christian church at large for all time.
The proverb applies to all aspects of life and culture, however. It seems to me that much of the frustration and disappointment we encounter is because we disregard this principal. We will attempt to game the system, seeking the harvest of the love of a woman, of money, or of power without earning it, without preparing for it, without being ready, should we appear to harvest it, to keep and husband it. In the same passage, Paul asks, "Will a man mock God?" Paul asks whether a man will "fool" God or trick him in respect to the principal of sowing and reaping. The question, of course, is a rhetorical one and has an easy answer.