Help! Help! I need serious help, I have a hard time discipline my kids, they are disobedient and don't like to

Listen and they are very lazy, the worse part is I know how to discipline them, I just lack the gumption to carry it through even though it is detrimental to their well being, especially since they are half grown any advice? To help me stand up and be a woman and a mother. They just have too much lip and attitude