Charles Duhigg, in his amazing book The Power of Habit, nails the importance of creating a keystone habit that practically guarantees success.
An example he uses is Michael Phelps.
Michael Phelps’ trainer, Bob Bowman, helped make Phelps the best swimmer in the world by helping him cultivate a set of strategic habits that made him the strongest mental swimmer in the pool.
He didn’t need to control every aspect of Phelps’ life—all he needed was to target a few specific habits that had nothing to do with swimming and everything to do with creating the right mindset.
Each night before falling asleep and every morning after waking, Phelps would imagine himself jumping off the blocks and, in slow motion, swimming flawlessly. He would visualize his strokes, the walls of the pool, his turns and the finish. He would imagine the wake behind his body, the water dripping off his lips, what it would feel like to rip his cap off at the end.