Being smart about Social Security involves making guesses about your life expectancy, and over the past few decades the longevity of retirees has trended steadily upward. But while that's good news for you, it could be bad news for the Social Security program.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, looks at the latest data from the Centers for Disease Control showing just how much life expectancies have risen for those of retirement age. In 1960, 65-year-olds could expect to live just 14 years to age 79, but now the lifespan for the average 65-year-old is 19 years, taking you to age 84. Similarly, 75-year-olds have seen their life expectancies rise by two years since 1980.

Dan notes that while those figures might not sound significant, they have major implications both for recipients and for the Social Security program. For recipients, longer life expectancies make it smarter to defer benefits. But for Social Security overall, more people taking benefits longer means more strain on the system. Dan concludes that general trends are important to know, but you still have to consider your own personal health and other considerations in judging the best decision for you.

Dan Caplinger and The Motley Fool have no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.