When I was a kid, I bit my fingernails a lot. I bit them so far down that it would make my fingers hurt. My mom was constantly telling me that I needed to stop, and I think she even tried ways of making it unappealing to me, but they didn’t work.
In eighth grade, I decided that I was done biting my nails. I wanted my nails to look nice, and I didn’t want my fingers to hurt anymore. I evaluated the situation and realized that I liked to chew on things, and my nails happened to be the most convenient. So, I started chewing gum. If I was chewing gum, I had no need to bite my nails.
When my nails started growing back, I became annoyed at their length, and chewed them back down. In the midst of painful fingers, I realized that I needed to keep my nails short as well. So, I began clipping my fingernails once a week, and voila, I stopped biting my nails cold turkey.
The gum chewing did become a habit that replaced the habit of biting my nails, but after a few years of that, I grew tired of it, and stopped completely. Chewing gum is not even remotely appealing to me anymore. About once every five years, out of some freak nervousness, I bite my nails, and am reminded of why I stopped.