Before I started cycling daily, donating often would leave me rather ill for a day or so; headaches and the like. Now I can't really tell. I still just cruise home at an easy pace, though it's tough; there's a nice long downhill on the way out of town and even without working I'm keeping up with traffic; it's tough to not hammer it when I get to the flats north of town and keep up.
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Work: the 8 hours that separates bike rides.