Please help I bite my lips & the inside of my cheeks it's so ugly how do I stop?

I've been doing this for years I just can't stop I bite chunks of skin off inside my mouth and on my lips chopstick doesn't help chewing gum doesn't help I don't know what to do I also bite the skin off around my finger nails I dont bite the nail off just the skin around it and people say to put stuff on ya lips but that doesn't stop me from biting the inside of my cheeks