Chain smoking and caffeine will give you cancer/neurological problems. Being overweight and not getting enough exercise will give you diabetes and other weight related problems such as early heart attacks (even if you're eating healthy). Exercising too much will give you early arthritis and joint/bone problems.
Living will cause you to get harmful diseases later in life. Doing anything is potentially fatal/life shortening, and the only way to prevent this is to live a boring, uneventful life.
I'm not advocating or defending smoking/drinking caffeine, nor do I do them myself. I hate smoking and I avoid caffeine at all costs unless I need that extra kick (maybe 1-2 times a month), but to knock one person's way of life over your own equally destructive way of life is narrow minded.