Need Help

i have been trying to quit from last week. i used to smoke 15 a day but when i decided to quit i came down to 3 - 4 a day. daily night while going to bed i decide that morning i will not smoke with a cup of coffee but i dont know why i tempt to have one when i grab my cup of coffee. I stopped buying pack of cigarettes but when i go back home from my work and see my flatmates smoking i tempt to have one and end up asking for it. please help me to get out of this.