Well, I just found a tool that might provide more accurate numbers. Check out DeathClock.com. You'll find an estimate of your moment of death
As the owner of the website suggests, its purpose is to remind you that "life is slipping away
One weakness in the site: it doesn't tell you how many seconds in a week (604,800), a month (approximately 2.5 million), or a year (31.5 million). So I could easily calculate that I'm looking at only about 20 more years, based on somebody's actuarial averages. (That sounds low to me--it has me dying at 74 years of age; but whether it's a bit low or about right, it's eye-opening.)
Even if I live to an "optimistic" age of not-quite-87, it's still eye-opening.
As for potentially extending your life
Enjoy!