I went from a 6 mile commute to a 30 mile round tripper this year. I only ride it three days a week at present as I cant get to work earlier enough on Mondays for meetings. Its tough at times and takes a big chunk of time out in the morning and evening. I combine my riding with the train, so it takes about 2 hours when its all said and done. I average about 14 mph with lights, though I dont have a lot of them. Im pretty tired by the end of the week to be honest, and if I had my way, my ride would be about miles shorter each way.

What I found at the beginning when I was riding sporadically was that it was actually harder, as my fitness was not as good. The ride is easier now with more days, but the fatigue does seem to build up by weeks end for me. Still, its kind of fun having 90 miles a week under my belt from commuting.

Good luck with it. Maybe you just need a break fora while.