For all have sinned and fall short of the Glory of God. Romans 3:23
Thankfully God forgives our sins when we ask and we then can receive his mercy.
But seriously we all have faults and have sinned. I see bad habits as continual happenings of a certain sin. My bad habit is involving the sin of greed. My weight does not disguise this sin. I know of this sin and regularly ask for forgiveness for it. I'm working on being so greedy and glutinous but it is a long journey and I have my ups and downs, just as everyone has problems with giving up their own bad habits.
I can see this habit developed when I was young, being told from a young age to eat what is put in front of you and then growing up in a family that enjoys socialising with lots of food around did well to develop this into a habit of eating lots of food. I enjoy food and am blessed with plenty of money so I can afford plenty of food. I hope to retrain my brain to add in the concept of enjoy food but less of it, only enough to be healthy and not overweight.
So what's your bad habit? Are you open enough to yourself to admit and confront your bad habit? Self-improvement comes through admitting something is not right and then doing something to change it for the better.