If it's something you can hold/touch get rid of ittt, put it out of sight.
Replace bad habits with good ones, find something positive that makes you feel whatever your bad habits make you feel (if it's something like an addiction)
Find new hobbies! Try something you've been wanting to do for a while, learn a new skill. If it's something you can end up having friends or a group for even better.
Set goals, work to achieve them and record your progress too! It'll help to keep you motivated.