"I am the greatest, I said that even before I knew I was." --Muhammad Ali
One of the best tests for figuring out if you're doing that which arises from your being is to modify Muhammad Ali's famous affirmation by saying out loud: "I am the greatest _____________ of all time," and fill in the blank with what you're doing right now. If this isn't really the doing that arises from your being, you probably won't even be able to finish saying this short sentence. And if you do finish it, the words will feel like bits of cardboard in your mouth.
If, on the other hand, the words roll off your tongue with fluidity and ease, you've found the right doing for you (and you probably already know that). Now, to achieve greatness in that doing, put aside any misplaced, misguided, culturally-induced sense of supposed humility you're supposed to harbor within your soul and say your own version of this affirmation as many times as you think of it throughout the day. Tinker with it to come up with your own wording to make it more personal to you, then make it your habit to think it and to say it as often as possible. Say it both to yourself and to other people. That's right, say it to other people. If you do, you will achieve greatness, guaranteed.