I had a panic attack thinking about it on the bus a couple of semesters ago and I still have trouble. I think about the world in very literal/scientific terms. The way I see it, we are all just walking systems of atoms that have come together to form a thinking being. When we end, those atoms move on to become part of another system.
If it helps, your body material will soon be part of the earth, which will eventually become part of something living again. In a way, when you die, you become part of a million more life forms
I think when that time finally comes I won't be afraid, even though I am now.
Also, for some reason, thinking about the mysteries of the universe help me cope with death. Even though I think in scientific terms, I don't think science will ever be able to explain where the universe came from and I think, if somehow we ever do find out, the mystery of death will be answered.