Focusing on our mortality makes us aware of how precious time is. It can spur us towards achievement, discovery and making amends when we've done wrong. The Buddhists know that and ponder death. To illustrate, here's a link to a meditation that I found on Youtube.
A couple of years ago I found myself a snuggly shroud that I though I'd like to have to mark my departure from this earth. Not that I'm planning on going anytime soon I hasten to add. There's people to meet, places to see, things to get done. But you never know. If I do pop off I might like one of these biodegradable burial pods by Capsula Mundi instead. They're planted in the earth with the tree of your choice for your surviving friends and family to tend. What would mine be? Well that's easy. It's got to be a silver birch!