Researchers who study the tug of war between will power and temptation say there's a biological reason a lot of our bad habits are hard to break.
Habits, such as smoking or eating junk food, give the brain an instant reward. Researchers say it involves dependence on a pleasure-sensing chemical called To beat it, doctors say avoiding stress and constantly repeating new behaviors such as exercising the same time everyday will eventually give your brain a feel good hit.
Also cutting out rituals associated with bad habits will make them easier to resist.