I am going to ask my two psychiatrists that I work with about this, but I'm curious to see what you think. I walk briskly 4 miles in an hour every day as well, and I'm very active. I haven't felt this good since I started taking lithium, and I realized that my depression lifted when I started drinking that amount of water 9 months ago; at the same time I started to taper my dose of lithium as well, so I wonder if there's a connection between my depression lifting and the lowered dose of lithium. Thanks for any insights you can give me!