I have gone about 10 days or so with no more than a sponge bath while hiking when I was younger. Otherwise I bathe every morning when I get up. Not only do I feel better when I am clean but to me a shower is like what coffee is to most people, it clears my head, wakes me up and gets me moving. Same deal with brushing my teeth. I cant stand to go without brushing my teeth, thats probably about 2X as important than a shower to me.