Habit change takes a long time. Once a new good habit is formed, sustaining it is easier.
You will be tempted to go back to old ways, however, if you persist in following through with your new habit, you will prevail.
Thoughts of the benefits of the new habit will be your motivation. For example, if your new habit has led to weight loss which makes your clothes fit better, makes you look sharper, happier and healthier; then these thoughts will help you to overcome the short-term temptation to indulge in over-eating or eating the wrong things.
Like any success in life, it is about persisting a little longer that will make all the difference.