I'm going to push the boat out a bit here and risk all kinds of criticism, but hey, this is a forum and I love to share things which have helped me grow, even if they are bizarre.
I read this book about a year ago by a guy called Napolean Hill called Think and Grow Rich. Andrew Carnegie (the richest guy in America at the time - in the 1930s) instructed Napolean Hill to research successful people. By successful people I'm talking about Henry Ford, Thomas Edison and many more. Several decades later there is a Napolean Hill foundation, funded by people who have donated parts of their businesses, saying it was Napolean Hills research (which I think took 30 years) that helped them achieve greater success than they could possibly have imagined.
So you get the idea, this is no nut job make a fast buck book and one that has helped improve the lives of those who have applied it.
Now there's a chapter in the book, Chapter 14 - The Sixth Sense. This talks about what would appear to be a bizarre concept. Napolean would hold meetings in his mind with council members where he would be the head. In his team he had Emerson, Paine, Edison, Darwin,Lincoln, Burbank, Napoleon (the French leader), Ford, and Carnegie. If he had a particular piece of work he was stuck on he used to give it to the council to deal with, and all behold the council members used to offer their advise. He said the members could be living or deceased, it didn't matter.
So I tried this with Da Vinci, when I was painting. Afterall why not access the master, and I received advise which I hadn't thought of, such as colour mixing on the canvas to darken or lighten a colour whilst the paint was wet. It's just like talking to yourself, but instead you are actively talking to Da Vinci, or whoever else you want to talk to. And if you listen and let go you'll hear in your mind a response, a thought, and in this way you can have a discussion.
I was brought up with the saying that talking to yourself is the first sign of madness, but reading what Napolean Hill bravely published, he had taken the madness label off this practise.
If you can get past the fear of madness, then this is potentially a hugely beneficial technique.