First, who are you accountable to? Saying "HN" is too easy. Find someone who will keep you on track with this. A close friend/significant other is a good start. Second, what's your plan? I didn't see one. You need to have some objective metric you will be accountable to.

Finally, be careful what definition of success you accept. Dont pin your self-esteem on this new change. You don't want that kind of pressure. HN is replete with self-congratulatory blog posts and Super Important Business Talk that is sometimes more posturing than reality. Change because you want to (it sounds like you do), and work on yourself as hard as you do this endeavor. Even if you crash and burn, you will come out far, far ahead.

You damage yourself when you couple your self-worth with your accomplishments. It's a natural tendency in high-achievers, but that doesn't make it a great idea.

P.S. don't be hard on yourself for being a late bloomer. Just work your ass off at something that you like.