Another friend, a musician, told me about a recurring dream he had in which he could see the exact number of days left in his life.
I decided to take the idea of number days seriously, and to revisit my earlier experience of counting down my remaining time on this lovely mortal plane. My hope was that a reckoning of my numbered days would help me account for how I spend each precious 24 hours, and to focus my attention and energy on those few tasks and projects I deem most important to me. Indeed, it might help me decide which ones are most important, which is the harder assignment.
What I wanted was a great big flashing sign that would show up on my computer and shout out to me how many days I had remaining. Then I would try to use my blog to record what how I spent the day to keep me honest. A wasted day would reveal its loss in the empty lower count the next day. I figured that mounting an automatic personal countdown sign should be pretty easy, and something that others might want to do as well.
My first step was to figure out my expected longevity. There are two ways to do this. One is to take the general average life-span for a guy my age in the US. To get that figure all you need to do is go the standard Life Expectancy Table (PDF), like the ones published by Medicaid. This will tell you the age at which statisticians expect you will die. For me, its 78.68 years.
The other way is to amend that basic figure with the plus and minus of your personal lifestyle, known illnesses and family health history. There are various websites that purport to make that calculation but I don't believe them. I believe they could make this adjustments with sufficient data, but I don't believe these websites have the proper scientific judgement or data to do so. So I'll stick the less exact but more trustworthy average age.
Either way you go, you take your expected life span in years
To turn that end date into a current "days left" you can use one or more free countdown clocks. There is a Google gadget that sits on your iGoogle homepage, called not surprisingly Countdown Clock. You enter your last day and from thence on it will show you how many days until then.
I also wanted a desktop clock for when I was not online. I am on a Mac and there is a tiny app called Days Left that displays the remaining countdown days in the dock. For Windows there is TimeLeft which I have not used. If you want to roll your own web-based countdown clock, there are some explicit instructions here for programming a customized one.