If you have ever tried quitting marijuana and find you suddenly got the urge to smoke weed or find every time you are doing a particular task or past-time you get the need to smoke wees.. these are triggers.
There are two typed of triggers which can cause you to want to smoke a joint or pipe or whatever your choice. They are 'Pattern based triggers' and 'Emotional based triggers'. Pattern triggers can be caused by a memory a time, a place, a person or a particular situation you find yourself in that when you were in that situation before you were often smoking marijuana. A perfect example is if you always liked to smoke weed after eating a meal, then this will create a pattern trigger based on that and when trying to quit you might find yourself immediately craving a smoke after a meal. Emotional triggers are more about feelings. An example of an emotional based trigger could be... previously you would find yourself arguing with your partner, you get angry and you smoke some weed to calm yourself down and forget about it... you have done that on many occasions, now it becomes an emotional trigger.
To learn to control these triggers you have to recognize the trigger and how it works and use self control. When a person a thing a place or an emotion makes you feel the need to smoke marijuana. You have to just push through it, recognize why yo are getting the trigger response and don't give in to it, just try to understand what is causing this reaction and you will learn to deal with it, and each time it happens you will understand what is happening and it will become easier and easier to not cave in to the trigger.