I'd also try adding some strength training to your regular exercise. It boosts testosterone levels (not in any amount that is worrisome :-) which is a factor in energy levels. Besides, it's fun, and good for you :-)

I hit the iron supplements every now and then too, especially if I'm eating a lot of vegetarian food. The way I get enough fluids is by making cups of tea (usually green, white or herbal) a regular habit throughout the day. They taste just good enough that I drink because I want to, not because I have to.