What is the hardest thing for you to give up in your life?

I am trying to quit smoking and i have pills that i was given to try to help me stop.Well to be honest i have been told to stop smoking from the hospital and i am going to give it a good try as the way i see it if i do quit good for me aswell as noone can moan and better still i will be able to show my friends that i have quit who have all doubted me.