I used to be religious, and when I lost my faith it took me a long time to come to terms with death. But much of it comes from coming to terms with suffering. Pain doesn't hurt less, but I've found a place for it and am often grateful for it.
The pain from loss is part of what it means to love, which brings the gratitude.
I also hope we cure death! As tech advances we may one day be able to stop or reverse death entirely.
I'm all for extending life as long as it means you get to do more cool stuff, but it's the stuff that matters, not the length. Eventually something's going to take you out, and it won't matter how long you lived, but what you did with it.