Well... I might go a bit contrarian again and suggest that the term "rest-day" seems to falsely connote weakness, when after-all, the Camino is all about slowing down and enjoying life as it occurs. I can totally get behind the "short-day" concept, as some cities are too big to absorb in one day, and some are so quaint they deserve more time than the "roll-in, roll-out" mentality allows.
Sadly, however, some people are so driven to knock off the designated stages, or to log 40-50K days, that they don't seem able to stop and smell the roses. But what is the point of that? I admit that I am totally anal about the weight of my pack, and scheduling in general, but I am more than willing to pull up short in a little lovely little town that feels right. This means having a little bit of flexibility in one's schedule, ie. rest days. We didn't know how our bodies would respond to our demands, and we conceded that it was quite possible that we just could not walk for 37 days straight. What's more, we decided that we didn't want to walk that far without a break. Sure, we lost folks along the way, but we were also able to meet that many more. Plus, we found that everyone had some stop time built in, and the next thing you knew, long lost friends were sleeping in the next bunk again.
Please don't feel that you must go a certain distance everyday. We met a lady who had 3 months to do the Camino. Her plans for the next day were to walk 4k,. She was also in her 70's, having a great time,. She was also journaling by hand, writing real-life post cards, and she was very happy!!! The Camino is supposed to be a spiritual journey, not a race to Santiago. Sometimes the best way to do the Camino (and yourself) the honor it truly deserves is to stop. For a mass, for a meal, for a quick chat with locals, to kick the soccer ball around with that group of school kids, to take off your shoes and soak your feet in that stream, to dip your head under that fountain, to have a beer with some new friends, to have a beer with some old friends from yesterday. Just occupy a bench in the shade and enjoy the world around you while you munch a bocadillo and air out your feet. It never fails to put a smile on my face, some joy in my heart, and some peace in my soul.
Happy resting!