Answers to Everyday Questions : how do i motivate myself to stop smoking and loose weight when my girlfriend and most of my friends smoke?

I have quite smoking twice before for two years each because i wanted to loose weight and because of the obvious health benefits. I did it cold turkey both times, and lost 80 lbs (280 lbs to 210 lbs) on atkins. I was really dedicated to going to the gym 2-4 times a week and because i seen results quickly on atkins that kept me going and also i wasn’t in a relationship at the time so I wasn’t influenced as much. Slowly smoking crept when I drink with my girlfriend and friends because I feel like when I drink I need something to offset it, or something, or take the edge off, I dunno and I smoke ciggarettes. Now it’s at the point where i’m smoking even if I don’t drink I don’t drink that often, but when I do I only like to drink liquor, I don’t like the bloated feeling from beer most of the time and I like to feel the effects sooner. I’m 6’3 so it takes atleast a 6 pack of beer for me to even catch a little buzz, where as it might only take 4-5 shots which i can take fairly quickly ( not too quickly) and it won’t upset my stomach, but I always want a ciggerete with beer or liquor nonetheless. Also even though I was at 280 at one point, and got down to 210 lbs, I’m back up to 235-240 lbs, and I really want to loose my weight again and stop smoking, I’m just not sure how to not want it when i drink with my girlfriend and friends I used to have good stamina when i was exercising and didn’t smoke, and could run 2-3 miles without stopping, and now my stamina is shot again, I’m smoking again, and I’m 30 lbs heavier. I know I need to have a backbone and just commit, but I am afraid I will give up again. I’m surpised because I even study psychology and read/listen to some really good self help material, but I just can’t seem to materialize it. I love to snack and I love food, but it’s hard to stay low carb all of the time because alot of times carbs are cheaper than meat, and I live with my parents so they buy the groceries most of the time, and I’m forced to eat what they buy, and I feel like they buy what they can afford. They lost weight on atkins too, about the same amt. as I did, but sometimes we dont have the money to buy the proper low carb foods, and then there are other times when they just don’t care and my mom will bring home a cheesecake or something. I don’t want to feel deprived, and I love to cook, and oodles and noodles are cheaper than hamburger, you know? This is all causing me to be larthargic all the time, and I want to nip this is the bud, so to say. I’m not trying to make excuses, even though it may appear that way, I just am not sure how to stay committed again. I’m sure I could start the process again, I just need some ideas for how to stay committed and strong when around my girlfriend, other friends, and for that matter when I am just by myself and want to snack because I’m bored or something. Any suggestions? Thank you everyone for your support and comments.