I don't see myself living much longer
How long have you been feeling like you don't have long to live?
Just lately I've been thinking a lot about death.
Did something happen in your life recently that caused you to feel that way? You should talk to a professional about  it.
No, I just have a feeling. Why are you being so nosy?
If you are having recurring thoughts about death, you might be depressed. You should really think about talking to a doctor about your mood lately. Think of how good you will feel when they are able to help you.