And in [exercising] knowledge [develop] self-control, and in [exercising] self-control [develop] steadfastness (patience, endurance), and in [exercising] steadfastness [develop] godliness (piety). —2 Peter 1:6
As believers in Jesus Christ, God has given us a new nature, but at the same time, we also have to deal with the old nature. When we allow the old nature to rule, we will follow our feelings instead of operating in self-control. Self-control is a fruit of our new nature, and all we need to do is develop it. We can develop self-control by using it, just as we can develop muscles by using them.
Exercising self-control is a form of freedom. You don't have to do what you feel like doing. You're free to do what you know is wise. Discipline and self-control will help you be the person you want to be. Don't ever say, "I just don't have any self-control," because the truth is that you do have it, but it needs to be exercised in order to be strong.