Usually I suggest that you check out the Step by Step Rich Thoughts process to help you get to a plac where you really do believe it, and feel it to be true.
However, here’s another idea: instead of saying ‘I am…‘ replace it with ‘He says….‘ or ‘She thinks….‘.
So the statement becomes:
He says I’m a successful business person, or She thinks I’m a successful business person.
It’s coming in the back door of the mind and catching it unawares. Try it with your next affirmation and see what happens!