@LisaLou - I tried a lot of products and homemade solutions for nail biting treatment, and none of them worked for me.
It didn't matter how awful something tasted, I would still bite my nails. Finally it came down to a matter of just making my mind up that I wasn't going to do it anymore.
For someone who has never had trouble with this habit, it is hard for them to understand how hard this can be. It can be done, but it does take conscious effort and will power as you mentioned.
I find if I am under stress the first thing I want to do is bite my nails. For the last 5 years, I have had long, strong and healthy nails, and I want to make sure I keep them that way.
For me that has been the biggest motivation to stop biting my nails. The nail biting nail polish may work for some people, but it was something that never worked for me for the long term.