I have this not so good habit which is nail biting especially when they are long already. So I hate letting my nails long and the moment they grows some inches I immediately cut them. Nail biting is also a sign of uncertainty for children but for the adult it's a stress and tension. Others are extremely bitters where they ended up biting their nails until they were hurt. The experts advice that holding some ball on your fist or playing marbles on the pockets will help. Another also advised to paint the nails with a bitter taste to stop biting them.