if thinking about death makes you happy, you're literally insane. but it shouldnt make you depressed either. we are just little biological creatures on a piece of dust in space, we didnt have to exist, but the right circumstances led us to do so, and therefore we should be content with the amount of time we have, but we shouldnt be looking forward to when that time is up. no one knows what happens when you die, even if you think you do, you don't. stepping into the unknown with no way back should not be a pleasant thought or a terrifying one. there are an infinite number of dna combinations that will never exist, just be happy that yours does, and don't worry about what will happen when it doesnt.
Just think of life as a video game for the ps2 and normal xbox, you played it for a while, had fun, you beat it, then eventually playing the same missions you already beat over and over got boring.. imagine playing those missions over and over for eternity, death doesnt seam as bad when you think about it that way.