I struggle with believing it's ethical to do this relaxation for myself sometimes (since there's always work and a million things one doesn't feel like doing that ought to get done), and it sounds like that's part of what you're asking. Sometimes being happier myself, as I am if I'm doing things for myself, lets me be more generous to other people. That helps me justify doing things for myself. However, I don't really have a sense of WHEN it's justifiable, so I'm not sure if this is much help. Obviously I can't blow off the things I ought to do that I don't feel like doing all the time.