We are, after all, all made of stardust. But for some curious reason (and despite all the evidence pointing to the opposite), a temporary chunk of stardust, that you associate with yourself, firmly believes that it is in a way separate from the rest of the world.
This sense of separation causes a lot of trouble and, among other things, the fear of death.
Let us explore this thin (and rather imaginary) membrane that separates you from the rest of Universe. Don't get me wrong, this membrane is wonderful - it's only because of it that everything exists. But it's also the cause of a lot of our troubles, so examining it closer is a useful (and interesting) thing to do.
Think of a soap bubble. Air inside, air outside and a thin temporary film that separates some air from the rest of it. The beautiful film is ever moving and almost transparent. The only reason we know it's there is because it reflects some of the sunlight that hits it.
But what if you were the air inside? How would you know that there is air outside and that it is just the same air? Would you treasure the film [too much] and fear the fact that the bubble will eventually pop?
You probably would. Because you can see other bubbles around you and they all pop sooner or later and after that their contents are nowhere to be seen. They seem to be gone forever.
Yet if you think about it, why should air, separated by a thin membrane from the rest of air fear the loss of this separation? Why would you treasure your boundaries more than your essence? When the bubble eventually pops, the air that was once inside re-joins the rest of the air and the wind mixes it all up.
In this sense, death is simply when you stop being [just] yourself and start being everything else. Why would you fear or mourn such a marvelous reunion?