Muhammad Ali has said this quote and I didn’t realize that he was a philosopher. Tony Robbins spoke of this as well, I wonder if he got it from Muhammad Ali from one of the many books that he read. It was a very important point to Tony and he has shared multiple times in his books.
Once you tell yourself enough affirmations that you want to belive it becomes a belief. You know that it CAN be true and CAN happen. But once your belief becomes a conviction you KNOW it is true and you KNOW that it can happen.
Be careful with your vocabulary if you used more words like know, can, etc. instead of words like maybe or possible then you will find that you can achieve more. Muhammad Ali is proof of that!