I have to admit, I feel much the same way. I tend to blame my rather blasé attitude toward the reality of my eventual death on the depression - I've spent so long dealing with suicidal thoughts that quite frankly, the idea of eventually dying doesn't frighten me any more. I also thank both Terry Pratchett and Neil Gaiman for their characterisations of Death-as-anthropomorphic-personification, since that helps a lot, too. Death isn't something to be scared of if it means I'm talking to one of the two constant characters from Discworld (the other one is the Librarian) or if I can look forward to a cheerful goth girl coming to meet me at the end of my life.

I suppose another contributing factor is the overall longevity of my family (three grandparents living past ninety) - if I go from that, I'm not even halfway through my expected lifespan, and to be honest there's more to worry about from life than there is from death (if I die young, at least I don't have to worry about a poverty-stricken old age and eventually dying destitute in a ditch somewhere).