It takes an average of 30 days to break one bad habit. Forming healthy habits in life is a must. To change habits requires a plan, a commitment and a desire. Overcoming bad habits requires replacing each with a good habit. In time as you become consistent in a healthy habit (eating healthy, walking, running, spending time with positive influences) each will become a normal part of your day. Eventually good habits will replace the bad ones.
Focus on finding good habits.  Joining a gym class is a great place to start. You will find people with discipline and desire to be their very best. Talk to them. Introduce yourself. Make connections and friendships with those who are positive influences and you will achieve a healthier lifestyle.