If you have been using cannabis for a long time, it can be hard to quit. You may begin to feel withdrawal symptoms as your body gets used to not having THC in your blood stream. These symptoms include: anxiety, sleeplessness, irritability and depression. If this seems like something that might happen then try cutting down on the amount of weed that you smoke each day or give up completely and see if these symptoms go away after a few days without smoking pot. The best times to quit are when you know that there is nothing else going on in your life besides giving up the habit. If things are going well with work or school then quitting will make everything seem better again!