You speak of bad habits and the worry they bring. Habit indeed has a wonderful power to beguile even those who are very earnest. But as it is powerful to entrap, so it is also easy to correct. If you will set over yourself for a time watchers, a trusted friend, a family member, someone who holds you accountable, you will easily break off from the bad habits, being closely watched. If you persevere in this even for ten days only, afterwards you will need no further struggle; all will be secured, rooted anew in the firmness of a most excellent habit.
But do not think that a short season of repentance is enough if you then give yourself up again to the old things. If after a long sickness you were made well for forty days, should you return to the food that caused the sickness, have you not wasted your former labor? You assign a little time for the health of the soul, or perhaps not even that, and do you expect to propitiate God? Are you but playing at repentance?
It is not the outward act alone that makes unclean, but the intention with which you do it. If your heart does not turn from these thoughts and habits, forcing a change is no gain. Do not increase your own struggle by carelessness, but persuade your soul, reason with it, and by grace bring it to a willing change.
Let this truth steady you: there is no one who is wicked by necessity. Good men reprove the bad; if any were compelled to evil, the good would be unjust. Yet they remain good, and their reproofs are a proof that we always retain power of choice. Therefore, do not be negligent. The fearful judgment is set before us: he that believes is saved, and he that disbelieves is punished. This is not cause for despair but for watchfulness. Even a bad man is not altogether bad, but has some good things. When God sends discipline in this life, it is a mercy, that having put away your sins you may depart approved and not be condemned with the world. Happy is the one who is corrected here, for thereby the few good things are not rewarded only here, but the soul is purified for the life to come.
Exercise your senses to discern good and evil. The babe puts even dirt into his mouth and cannot distinguish what is wholesome; but the full grown, by reason of use, has his senses trained. Be not such a babe, lightly carried about by every impulse. Instead, taste the solid food that belongs to the perfect, and by persistent training learn to reject the bad and hold fast the good.