In The Sacred Romance, John Eldredge writes:

As a young boy, around the time my heart began to suspect that the world was a fearful place and I was on my own to find my way through it, I read the story of a Scottish discus thrower from the nineteenth century. He lived in the days before professional trainers and developed his skills alone in the highlands of his native village. He even made his own discus from the description he read in a book. What he didn't know was the discus used in competition was made of wood with an outer rim of iron. His was solid metal and weighed three or four times as much as those being used by his would-be challengers. This committed Scotsman marked out his field the distance of the current record throw and trained day and night to be able to match it. For nearly a year, he labored under the self-imposed burden of the extra weight, becoming very, very good. He reached the point at which he could throw his iron discus the record distance, maybe farther. He was ready.

The highlander traveled south to England for his first competition. When he arrived at the games, he was handed the official wooden discus—which he promptly threw like a tea saucer. He set a new record, a distance so far beyond those of his competitors that no one could touch him. For many years he remained the uncontested champion.

Something in my heart connected with this story. So, that's how you do it: Train under a great burden.