The key to pattern change is described as neuroplasticity. Neuroplasticity is the phenomena of being able to create a new normal pattern. Any habit you have that you want to break has come about gradually and became plastic. The same process that develops bad habits is the same process that develops good habits and breaks bad habits.
Essentially, anything that is repeated frequently and consistently will eventually become a pattern that you do without thinking about it. If you bite your nails, it’s likely that you started biting them when you were anxious. The more frequently you were anxious, the more frequently you would bite your nails. In order to break this habit, you would need to calm your nervous system consistently and frequently. Eventually you will stop this bad habit because you are able to identify and treat your underlying anxiety. If your anxiety is better but you still are a nail biter, all it takes is a subtle cue like wearing gloves or even painting your nails.
All habits would have their own solution but the beginning is resetting the nervous system so we can be more aware of our patterns. Once you can calm and then institute change frequently and consistently you can make a neuroplastic change. A neuroplastic change can be yours for life and is definitely worth the initial time investment.