1 Mark Zuckerberg works 10-12 hours a day
When asked about the number of hours he spends working, Zuckerberg said that he works 50-60 hours a week, which is 10-12 working hours per day (See also how Mark Zuckerberg came up with the idea of Facebook).
2 Spends 1 hour/day learning Chinese
Mark Zuckerberg announced at one point that he spends 1 hour per day learning Chinese. However, it's not clear whether he still spends the same time every day doing that.
3 Mark reads a book every other week
Mark Zuckerberg said that he reads a book every other week. This could mean that every other week, Mark spends about an hour per day reading a book (See how to read a book really fast).
4 Mark goes to the office 5 days/week
According to a designer who works near Mark Zuckerberg, the latter comes to the office 5 days a week. This doesn't mean that Mark doesn't work on weekends, but just means that he takes two days off from the office (See also How Mark Zuckerberg spends his money).
5 Mark thinks about Facebook 24/7
Mark said that although he spends 50-60 hours in the office each week, he still thinks about the mission, referring to Facebook's mission, 24/7 (See also Why Facebook Succeeded).
6 Mark checks Facebook all day long
Although he doesn't post all the time, Mark said he checks Facebook all day long.
7 Mark spends a significant amount of time reading about successful people
According to sources in Facebook's office, Mark can spend 70-80% of his time reading about successful people online.
8 Mark Zuckerberg travels very often
According to sources in Facebook's office, Mark travels a lot, but he is also present in the office most of the time.
9 Mark works out 3 days a week
Mark Zuckerberg said, as he answered a question online, that he works out 3 days a week and it's usually the first thing he does as soon as he wakes up.
10 Mark Zuckerberg walks his dog often
Mark said, as he answered questions online during a Q&A session, that he tries to walk his dog whenever he has time.