Commuting is 100% of my exercise. I stopped for 3 months due to other priorities, and wound up on blood pressure meds. I've restarted and am now able to to taper off the meds.
I'm actually starting to do a little time on the treadmill every week. Not a lot, just a couple of miles once a week, for some impact.
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Work: the 8 hours that separates bike rides.