So, some background.
I've worked (in lessons and alone) with enough horses that lean at this point that I'm fairly confident with what to do about it. But I thought I'd see if I could get some more pointers anyway, because you never ever stop learning when you're working with horses.
The horse I'm working with a 14 year old QH mare named Mufasa (Muffie). At the moment I am her only rider, and I have ridden her a few times in the past, but I work for her owner now and get to ride her in exchange. She hasn't been ridden for a while, and is rather overweight. (Any suggestions on how to get her back in shape would be awesome too.) She doesn't lean badly at the walk, but at the trot she is constantly falling to the inside. She does this at the canter, too. But in my experience it's best to tackle it at one gait before paying too much attention to the next. (Especially because she's fat.)
So, suggestions anyone?