One thing I did when I quit: I gave myself permission to do anything else. Granted, I didn't have any illegal habits or anything that was going to kill me right away, so take that off the table if you need to. But things like junk food, alcohol (as long as you're not an alcoholic/persistent drunk), TV, gaming, etc.? Go wild, so long as you're not putting your life, freedom, etc. in danger. It can help to alleviate the stress. Of course it's also good if you can distract yourself with good hobbies. Point is, whatever you do, take smoking off the table and do anything else in order to get through the cravings. After four days, the nicotine's out of your system, and from there it's a psychological fight.