First of all, congratulations to Me - not everyone makes it to 45. I'm healthy, still physically look like a pro athlete, and have all my teeth, and can walk on my own. Those are accomplishments.
This letter isn't gonna be a long celebration of you. You've been telling yourself plenty of good stuff every day. No need for me to waste time with more of it. Let me give you some useful feedback - constructive criticism, if you will - that you can share on that blog or podcast of yours. By the way, you have NO IDEA what those have become now. I mean, WOW!! All I’ll say is, strap on your damn seatbelt.

Now, onto what you need to know.
First off, you waited too long.
You waited too long to start reciting a daily statement of your life, as you saw it becoming, out loud every single morning. You would've had all this years ago.

You waited too long to start living exactly as you wanted to live. Too many hours and days wasted on people, places, thoughts and things that you KNEW didn't belong. But you allowed them to stick around, calling yourself being “nice,” “loyal,” and “considerate,” whatever the hell any of that means. Was that wasted time worth it?

Rhetorical question. Here’s another one -
You waited too long to go bigger - in your ideas, your actions, and your vision. Your tiny vision didn't exactly stop you, but it was like planting oak tree seeds in an 8oz water glass. There was only so far you would've gone thinking on such a small scale. I'm glad you figured it out before wasting so much precious potential. "You waited too long to go bigger - in your ideas, your actions, and your vision." 
What else?
In selling yourself, what you offered, how you ran your business... You really tried to do it all by yourself, as if you were some sort of foolish, Vegas Strip knock-off Superman. WTF?!?!

Dude, look in the mirror -- you ain’t even White! And you don't have hair.
You figured it out, though, and got a goddamn staff around you.  Then, finally, you could do what you do best, and do it much better at that. Better late than never.
But I'm not done.
You held yourself back, Dre. "You held yourself back, Dre." 

You over-thought things. Even though you made this crucial mistake much less often than the average person, that doesn't make it better (we don't compare yourself to the average person anyway).
Too much time spent on thinking and not enough action.
You allowed that bad advice that maybe you were “doing too much” slow down your progress. You curtailed your activity after reading all those productivity-tip blog posts.

Dammit.
Start creating your own success with The Mental Workbook.
You were on the right track to begin with! There are very few failure cases of “doing too much.” You were afraid of THAT???
You finally figured it out: most people never do enough in the first place to ever even approach doing too much (I heard it on your podcast). Doing the most is what helped you become YOU anyway. How'd you get good at basketball and build your name on YouTube? Double down on what works!

I will credit you for putting a stop to the comparing and competing you'd always do in your head. Silencing that constant chatter was all you needed to finally realize you were far better than anyone you'd be “competing” with anyway. Funny how your (partial) focus on those comparisons made them real.

The power of the mind is not a joke. "The power of the mind is not a joke."
Again, better late than never. What’s done is done.
Enough dwelling on the past anyway. Let me give you a glimpse into the future that’s bigger than you us.

The internet and social media are going to dominate lives even more than they do now. You'll look back at right now and laugh at how you thought it was something. Where you're at right now? 2017? That’s like black-and-white floor model television (google it) compared to now. With no cable channels and no remote control. Things changed so fast over the last decade, 2017 is like the media Stone Age.

What I will tell you:
Keep recording videos. It will become a living, breathing history book, authored by you. And your work will pay off in ways you couldn't see from there. But you will see it.
Podcasting in 2017 is in its infancy. Keep sharing value every day. The payoff is going to be CRAZY.
Write more books. I know, you're working on one right now. Good. Finish it, then start the next one. And whatever you have to do to get your books in people's hands.  
Do EVERYTHING you want to do, as soon as possible. Never hesitate. You already preach how time is of the essence and how moments should never be wasted. So, live it out to the fullest; the payoff is well worth it. Hell, OVER-live it. The last thing you want at my age is the regret of what you could have done.
There’s a lot more I have to say to you, but I'll wait a few years to let you in on it. I know you're busy building our future.

Get back to it.