Not only has the average retirement age dropped over time, but the life expectancy has also ballooned. As a result, tetirement planning is taking on a whole new depth that didn't exist a couple of decades ago.

No longer do we need enough money to last only 10 years after leaving our job; we need much, much more. For many people, this reality has led to a sense of anxiety about not having enough to live on during their golden years.

But in an interesting twist, the increased length of retirement has also led to an increased interest in working beyond age 65. In fact, a recent survey suggests that 72% of soon-to-be retirees are planning to work in their retirement years.

And here's the real stunner: Many of them are doing so for non-financial reasons. In fact, a recent survey broke down those working in retirement into four groups. Each is different and has its own unique financial circumstances and reasons for continuing to work. But one thing is for certain: You want to avoid becoming a member of the last group at all costs.

To see where you might fit in, check out the following video by The Motley Fool's Brian Stoffel.