Fairly often. I'm not a young man anymore, so I've got to be realistic about such things. If I'm lucky I have another 30-40 years, but given my family history, especially on my father's side, another 10-20 years is more likely.
Also, I had recently come across a post by somebody dying of cancer pouring out his regrets and I couldn't help but wonder what he hoped to accomplish by dwelling on the past because he no longer had a future.
Perhaps he was seeking closure/ some sort of consolation.