If you’re in retirement now, or approaching it, you know there are many things to consider and many decisions to be made that will be important in determining your financial well-being for the rest of your life. Among the most crucial: estimating how long you’ll live. After all, no one wants to outlive their assets.

I’ve had conversations about these topics with many friends who have retired in the past several years, and the most surprising observation to me is how many people underestimate how long they’ll live in retirement. In fact, many people really don’t expect to live very long, say even into their 80s.

Sometimes their belief is based on one of their parents passing away in their early to mid 70s, and sometimes it’s because they cite the life expectancy as being in the late 70s for a man and low 80s for a woman. However, this is a misunderstanding of what life expectancy is, and it can lead to very serious financial consequences down the road.