In the video above, he explains why:
In all the studies of procrastination, what they’ve basically said are two things: number one, you can’t find some work reward that’s going to take the place of procrastination. Right? If the reward for procrastination is that you get to spend five minutes distracted by Facebook, you have to allow yourself to do that. That has to be part of your work day. If you need five minutes every hour to look at tweets or to just surf the internet, you need to schedule that into your schedule, allow yourself to do that. Because when people start procrastinating, what they’ve done is, they’ve tried to ignore that urge. They try to deny themselves time on Facebook or time surfing the web. And then all of a sudden, it erupts and they go and they say, I’m just going to check for five minutes, and 45 minutes later, they’ve lost, you know, all of this time. It’s because they haven’t accommodated that need.
So give yourself five minutes every hour to look at cute baby animals if you like (hey, LOLcats might even make you more productive).