How can I wash my hair without shampoo after a workout?

I know it's bad to shampoo your hair everyday, but here lies the problem. I workout mostly everyday and get pretty sweaty. In fact when I take my hair out of the hairtie it doesn't even fall out (it looks like a mullet held up by sweat lol). I don't see any way around using shampoo everyday, but I don't want to damage my hair. Does anyone else have this problem and what should I do?