At least once a day, although being a part of my college's rowing club usually bumps that up to twice a day. But I need to feel at least somewhat clean; my hair gets horrible and greasy if it goes for more than a day or two without being unwashed. Also, when I've not had a shower, I find I tend to sweat more (or at least feel that way) and just feel icky and lethargic until I wash myself off. Occasionally, I might miss a day (usually Saturdays) but it's rare for a day to pass without me jumping into the shower at some point.