How to break bad habits?

According to the great minds, it takes 21 days to break a bad habit. Easier said than done. I stopped biting my nails as a personal goal through some tough times and thus far, success. This is proof that a habit can be changed.

There are several ways you can stop fiddling and plucking ect wear gloves indoors for a while or put butter on fingers and when you try to pluck or pick your hands and fingers will slide off your face,sit on your hands,put something horrible on your finger nails so when you put them in your mouth you get a nasty taste,take up gardening, read a book, bake a cake, keep your hands busy and occupied take up yoga or something to relax your mind.It will not happen over night you have to retrain your brain and hands,it will work so stick with it, good luck and merry christmas,suzzy.xx

I used to have a lot of bad habits such as nail and pen biting, eye rolling and leg shaking. I was able to break all except the last one. What I did was deal with one thing at a time until I got used to not doing it. The leg shaking is something I can't stop though. I am even doing it right now lol. I don't realize I'm doing it most of the time.