Forget religion for a moment, “it’s easy if you try”. This, from Hinduism’s Karma theory on the Brihadaranyaka Upanishad, is true. I know it, you know it.
“Now as a man is like this or like that, according as he acts and according as he behaves, so will he be: a man of good acts will become good, a man of bad acts, bad. He becomes pure by pure deeds, bad by bad deeds. And here they say that a person consists of desires. And as is his desire, so is his will; and as is his will, so is his deed; and whatever deed he does, that he will reap.”