I try to ride a lot on my days off, and I feel that I may be over doing it. This week I really ate poorly too due to graduation party and other family events. So I probably over did it a little. I'm working on building my endurance. As a mountain biker I am more used to bursts of speed due to up and down hills. My commute to work is pretty much flat, so it's more consistent work effort. I try to ride hard both ways to get the most out of the ride. Maybe I should alternate between hard and easy rides for the time being until my legs are more adjusted to the ride? I also try to ride at minimum the same amount of miles on my days off to try and train more too. Maybe if alternated hard and easy days more often, my legs wouldn't feel so worn out. I also stopped weight training on my legs due to more riding. I keep reading on here people with 25 mile each way commutes. Mine's only 9.5 each way and feel that I should not be as worn out as I am.