How do nails grow?
NAILS GROW FROM MANY THINGS INCLUDING THE SUN, NUTRIENTS FROM THE THINGS ALL AROUND U AND MANY MORE THINGS. HA!!! Nice answer I happen to be an expert on nails and not just painting them. Well your nails grow from protein. They also grow like your skin because that's what they are a modified type of skin. When your old nail cells die. Your new ones push them out of the way. Your old ones create a protein for your new ones causing them to grow 2 mm per month. To keep them healthy you should use lots of moisturizer. With your toenails cut them straight across. Not curved otherwise it will cause an ingrowth that pierces your skin. Your fingernails can be cut curved but it's better to do them straight across. Yes I know this answer is way better than the other one.
To break a habit you have to believe you can do it. Your nails have 2 main layers the hard nail and the soft flesh. It takes about 3-4 weeks for your nails to start to grow. If you bite your nails file, sprinkle salt on them, leave them in water for 10 minutes and it will help your nails grow a lot.