3. Use Hypnosis or Subliminal Messages
Hypnosis can be a really effective tool when it comes to breaking habits like biting nails. Hypnosis is when you allow someone to put you in a trancelike state and then speak directly to your subconscious mind. Your subconscious mind is where all the decisions happen.
When you allow someone to speak your subconsciously find through hypnosis, the lessons that are learned there and the beliefs and thoughts that come from it are much stronger. You may have to visit a clinical hypnotist in order to use this therapeutic tool, but if you do not have the budget for that, then you may want to consider subliminal messaging.
Luckily, with how often we use or tablets, computers, and phones, there are programs and applications that will flash subliminal messages across your screen that sticks in our minds. Subliminal messages only last a fraction of a second, but your subconscious mind will notice them and remember them.