Sometimes writing is sitting at your computer doing research all morning. Ferreting out one fact leads to an interesting article, leads to a photo essay, and then somehow you're down a Buzzfeed spiral of funny gifs.
You find it's been two hours, your original question is answered, but you now have three more interesting ideas. The only thing you've written all morning is a dozen hilarious texts to your best friend about Internet junk and an email to your mom about that one recipe she used to make, you know, the one with chicken.
You wonder if the day was a success. Well, you found the answer to your question. and you have new story ideas to mull over and work up into something. That's progress, right? Yes.
On the other hand, it's not words on paper, and that's less useful. But then, some days are like that: a little work, a lot distraction. In the end, you have the answer to your question and a place to start tomorrow's work. A step forward, even a small one, is still positive movement.