In reply to vertical thrills:
Been doing a lot of thinking along these lines over the past year or so. When I'm climbing, biking, doing anything dangerous, it's not death that enters my mind, but pain. That's really what stops me doing anything too stupid as I never consciously put myself in a position where there is (in my opinion) a huge risk of death, but often I can see how some actions might bring about some severe pain and suffering, and this brings the severity of dangerous things I do down another level.
When I do think about death, it's usually at night when I can't get to sleep. I sometimes think 'I am alive, therefore one day I will die, and there isn't anything I can do to stop that', and the enormity of that realisation is sometimes overwhelming.
However, I also agree with tlm that the impermanence of everything can be comforting. You could be the most villified person in all of human existence, but one day the Sun will expand, consume the Earth and there won't be a trace of evidence you ever existed. You could look at this in a nihilistic sense, but I prefer to take from it that the small things really aren't worth sweating over.