When I was a child, my grandma warned me, sew on Sunday, pierce an angel. Later on, I realized that for her, sewing was work. Not for me. Treating it like work goes against my grain, but I understand what you mean - you can't take a vacation if you don't have a job, if you are always on vacation. And yes, I take breaks from sewing all the time, and don't feel guilty at all. Do what you have to do, and have all the fun you can squeeze in.