I am very pleased with my progress.
My muscles are responding quickly--I am already much more confident in the saddle and able to do rising trot for much longer periods of time, and I don't feel lower back strain at the canter like I did last time.
I'm also noticing that a lot of my muscle memory around cueing the horse is still intact, which is pretty remarkable given the amount of time it has been since I rode. I was able to do walk-canter-walk transitions without difficulty, for example.
I also realized that at this stage of my life, I could purchase a Grand Prix dressage horse and afford the training necessary to ride at the highest levels. That's kind of an interesting thought, one I will entertain after I manage to play high-goal polo.
Anyway, I am enjoying riding again and getting to interact with horses. Horses are really special creatures, and it absolutely makes my day when I get to interact with them. It has been way too long; doing this is so good for me.