Because in the process of rationalizing your own decision for smoking, you'll start to become more understanding of everyone else's bad decisions.
On an unrelated note, go to church this weekend. And don't feel bad about going if you haven't been since Christmas, and you don't want to be the cliche person who only goes to church on holidays. Be that person. Because if we even get a glimpse of what the resurrection of Christ really means for our life, it's a complete mind-blowing life-changing switch. And it's totally worth pursuing. Happy Easter.