From existence to what?

I lean back in my chair and look at the light fitting. The light usually on, burns my retina slightly, with it's a ghost image of the bulbs. As I relax I take note, I hear the birds chirping the car passing then I become aware of the PC fan haven't heard it before but it's loud! I didn't hear it until I drew my attention to it. Then I feel my relaxation, I note my breathing, my chest rising and falling, relaxing. Thinking one day it will all end, maybe today, tomorrow, next week, NOW! 5 years time, 20 years time. That day will come. Will death steal up on me, or maybe I won't see it coming! Will there be pain? Will I accept it? should I ask somebody whose near it what they think? should I ask somebody who is terminal what they think? Bloody awkward conversation I reckon! I think its safest to just relax and contemplate the future, when that line is crossed, from existence to what?