Yesterday we told you about Mark Zuckerberg’s 2011 challenge to himself: “The only meat I’m eating is from animals I’ve killed myself,” the Facebook founder and CEO told Fortune in an interview.

As we detailed, an inkling of “Mark Zuckerberg’s new challenge” popped up on his private Facebook page a few weeks ago. On May 4, the 27-year-old billionaire told his 847 friends: “I just killed a pig and a goat.”

His friends’ reactions, as you might imagine, ranged from concern to confusion to disgust. How did Zuckerberg respond to them? He posted his own comment later that day. Here’s the full text of Zuckerberg’s May 4 comment on his private Facebook page:

Every year I have a yearly personal challenge. It’s a good way to explore different things I wouldn’t normally do and challenge myself. Towards the end of last year I reflected a bunch of how thankful I was that we were building so many good things and things have gone well so far and I decided to make this year’s challenge around being more thankful for what I have. I struggled for a while about how to implement this, but eventually decided that forcing myself to get personally involved and thank the animals whose lives I take in order to eat them was the best day-to-day way to remind myself to be thankful. So every day when I can’t eat meat I am reminded of why not and how lucky I am, and when I do get the chance to eat meat it’s especially good. This challenge also has the benefit of making me generally healthier, and I’m also learning a lot about sustainable living.