I'm 40 and find myself thinking of death quite a lot these days although I think I might have always thought of it more than average. I don't have any set beliefs on religion or the afterlife although I am open minded the reality is that I just don't know. I know that some respected physicists like Sir Roger Penrose have interesting things to say on the nature of conciousness and the continuation of that conciousness after death as well as the scientists at the Max Planck Institute. I'm not frightend of death but curious about what happens after, although not in a rush to find out either!
I suspect as you get older we all think of it more and encounter it more as those we love grow old and die, but I wonder if its also that we are mentally preparing ourselves for death?