Short Run, Long Walk

I was bored yesterday so I ran about 20 minutes but was losing motivation, so I walked for another 80 minutes. I figured, I'm just watching tv, so why not? I'll tell you why not. My right knee is killing me. The back of my knee hurts so badly. I was walking at a pretty good incline (5%) and I think that might have had something to do with it. OY!
No running today b/c of class, and then tomorrow morning I'll probably run since I've got a weekend away at my parents!!