20 years.

There is an old story of an ambitious young person approaching a master and saying, "I want to be your student, your best student. How long must I study?"

"Ten years."

"But ten years is too long. What if I study twice as hard as all your other students?"

"Then it will take twenty years."

There is a river of life all around. But you can't push it. Try softer. - Ortberg