Similar to a New Year's resolution, Facebook founder Mark Zuckerberg picks a new challenge for himself each year. Five years after founding Facebook, he began posting the annual challenges to his social media following.
From ditching his signature hoodie for a "more serious" look to killing his own dinner, his annual challenges have ranged in complexity, time commitment and difficulty.
"Every year I take on a challenge to broaden my perspective and learn something about the world beyond my work at Facebook,” Zuckerberg wrote on his Facebook page.
We took a look at the last nine years of challenges: