This past summer I was in the same boat. I wanted to ride in every day, but only managed 2 or 3 times a week. Long hours, and always on my feet. I once wore a pedometer into work, and after 9 hours I logged over 19,000 steps. 8.5 miles RT commute, with a biggish climb at the end. I'm not working the same number of hours now, but I'm still only riding in once or twice a week.