What a difference 10 months of retirement makes!

TMZ snapped up the above photo of David Letterman — bald on top, bearded and flowing from the chin — jogging on March 22, 2016, on St. Bart’s.

I like to think Letterman inherited “the Santa Clause” to become Santa Claus upon his retirement from late-night TV. OK, a skinny, in-shape Santa! How do you imagine the comedian and TV host’s new role as he prepares to turn 69 in April?

Here’s a look back at the evolution of the Letterman beard and hairdo over the past 10 months…

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May 20, 2015: Hosting his final episode of Late Show with David Letterman on CBS

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July 10, 2015: Surprise guest on a tour stop with Steve Martin and Martin Short

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Nov. 30, 2015: At his alma mater Ball State University, moderating a conversation with Spike Jonze and Bennett Miller

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March 22, 2016: Jogging on St. Barts