The day before my back surgery, I decided that while I was healing, I would change a bad habit of mine that had been bugging me: crossing my legs.
(I had originally pondered attaching half a tennis ball to my knee with a rubber band, thus making it impossible for me to cross my legs, but *lucky me* the surgery came first.)
First I made sure I knew why I wanted to change the habit:
It's not good for my back or thighs. It puts pressure in places I don't want it to.
Then I decided how I would change this habit:
Uncross my legs whenever I found myself crossing them.
It was easy to stop crossing my legs the first few weeks post surgery because it was somewhat painful to do so. Once things got back to normal, the urge came back. And I had to continually fight it. And once in awhile I still do, but for the most part, the habit has been broken.
Next up... not sleeping scrunched up on my left side. (It's borking my shoulder.)