I have smoked 20/day since 1990 and have just given up. Over 4 weeks without a ciggy atm and I'm not stressed at all.
A couple of tips that I think helped me...
1. Don't set a specific date to give up... You'll only get stressed about the prospect of giving up as the day in question draws closer. Result = greater probability of failure.
Instead, just wait for a day when you are in a good mood, relaxed, and preferrably busy, then just chuck your pack of cigs away and start from there.
2. There are two parts to giving up smoking imo; the nicotine addiction itself and the habit of reaching for a ciggy at specific times.
I recommend nicotine gum when you first give up. This will help in the beginning with the nicotine withdrawal while you are trying to deal with kicking the habit of actually reaching for a ciggy without even thinking about it.
Everyone is different so what what works for one might not work for someone else.
Just keep trying