Hey divemama, welcome to the db family! Interesting thread. I've wondered the same thing from time to time. You're off to an awesome start! Mentally, I've been playing around with some self meditation stuff off and on. I found it in a triathlon mag a few years ago and tried it in my living room. Thought I would try applying some of the concepts to freediving.
I have a mantra that I go through. It's short and simple. Slowly and very relaxed I mentally keep saying, 'my mind is relaxed, my body's relaxed, and my heart rate is slow and calm'. While going through that mantra I also pretend that there is a scanner going up and down my body looking for tension. If my 'mental scanner' finds any tension I just remind myself to relax.
Other than that I try to 'feel' the water. Instead of thinking of the water as an obstacle that keeps you from breathing, think of it as holding you and think of yourself as gliding through a friendly, 'home' environment.
I don't have any reason to think that this is better than anything else out there, but it's what I try to do. I have my good days and bad days, but it helps me feel one with the water.
Confucious say, that's all folks!
.....and anderson, if you're reading this, I'm still a freediver who spears for a hobby.....at least I'm hoping to ......
Later divemama, and keep posting!
-mike