Set up your life in a largely different way, so it is more conducive to healthier living and success, and less conducive to continuing your negative habit. You have to change the way your life is set up, because the way it's set up now allows you to easily continue your negative behavior.
Change aspects of your environment.
Certain objects are allowing you to continue your negative behavior. Get rid of them and replace them with objects that are conducive to a positive change.
Example 1: Overweight?
Food: Get rid of all the junk food in your house - all the food that's high in sugar and fat. If you can't convince your family to do this, at least get rid of all the junk food in your room, in your locker at school, in your dorm room, etc. You can't eat what isn't there so throw it out now. Forget what you paid for it. The cost to your health is much more expensive. Replace the food in your home with fruits, vegetables, low fat yogurt and other healthy foods.
Wardrobe: Get rid of your baggy clothes that conceal your weight. These make it easy for you to remain overweight and leave room for you to gain more weight. Retain the clothes that fit you just right or that are a bit tight. If you gain weight do not buy larger clothes. This will require you to manage your weight to regain comfort.
Example 2: Drug abuse?
Get rid of your drugs. Don't carry money with you to the places where you buy the drugs. Get rid of ashtrays and other equipment you use for using drugs. Break off from a group of drug abusing friends. Spend more time with family or if they are involved with drugs, join an athletic team or youth club. You can't smoke, sniff or drink what isn't there, you can't buy drugs without money and you can't borrow drugs if the people around you don't have them.
GET UP RIGHT NOW AND TRASH ANYTHING HOLDING YOU BACK FROM ACHIEVING THE GOALS THAT YOU DESERVE!
Make time for health and limit time for bad habits.
Make time for...
"I just don't have time," is a typical excuse for many people. The truth is that you are the one who schedules a significant portion of your time. If you get the recommended 8 hours of sleep, you have 16 hours for each day. 7 hours might be spent in school. The remaining 9 hours are yours to schedule. You must do certain things within that remaining time, but it is always possible to set aside time to take care of your body. Eliminate procrastination. Eliminate unhealthy activities. Eliminate unnecessary activities that take time away from caring for your body.
All the items listed above (sleep, exercise, a healthy diet) are crucial to daily performance and to your body's health as explained within this web site. Let's take exercise for instance. If your life is so chaotic that you never have time to exercise, you need to cut some aspects (especially unhealthy aspects) of your daily schedule to make time for exercise. It might mean quitting a part time job if your parents can support you. You might skip a television program or tape it so you can watch it on the weekend. You might want to buy a daily planner to organize your time, or limit phone conversations. The fact is, without exercise, you will have a weak heart, a weak body and a weak immune system. Your body's health is more important than entertainment, extra spending money, or even good grades. As long as you get enough sleep, exercising releases chemicals (called endorphins) that have been proven to improve productivity and the ability to concentrate on work. So taking time to exercise before school or before you do your homework might actually improve your performance in school.
Limit time for...
Most urges hit during times of boredom. Times where you feel there's nothing else to do. Times during which your brain is unoccupied and thus able to daydream about those urges. Don't give yourself that time. Fill your schedule up with fun stimulating activities and obligations (like exercise), so by the time you get to your room at night, the only thing you want to do is fall asleep. If you do find yourself with time to daydream, think of all the things you accomplished that day and all the things you plan to accomplish the next. Try volunteering, clubs, sports, dance, etc. Occupy your mind.