I think a lot of the initial stuff from OP isn't as true as it seems lol! I've seen people who have smoked cigarettes, drank alcohol and not exercise but live to be 90. It's all about contentment. Don't be depressed. Be happy and you should (hopefully) live a long life.
Also, I've had an insane stressful 4 years. I don't think it means I'm going to die when I'm 50.