Again--trigger warning

So I'm a 30yo smoker, with high blood pressure, high cholesterol, and pre-diabetic. Diabetes runs big time in my mom's family (my grandmother and all her 7-8 siblings have it despite not being overweight). The thing is, I'm having a hard time taking any of these health issues seriously because part of me really thinks like, "so how much younger does that mean I may die? I don't want to be here!" So I don't change anything. My mother has been lecturing me about my health when she found out stuff. I know my thinking is messed up, but I just don't know how to get serious about taking care of my health. When I'm doing well, I can take better care of myself somewhat, until depression rolls in and I wish I was dead.

I can't be the only one who struggles with this. Has anyone found anything that helps them want to take care of themselves (or just do it despite not wanting to)?