Can Do Attitude

Apparently I was told, “You have a ‘Can Do!’ attitude.” This is news to me because I never knew that I had an attitude that could be labeled as positive. What really sucks about being labeled this was is that it means that I get more work handed to me. Not kool (Yes I spelled it wrong, I like it like that).
You see, in these tough economic times, a coworker was let go and his position was totally removed (Sucks, but I never really liked the guy. Sorry dude). So in the meeting where we were all told that he was going to be let go, apparently I had a look on my face that could kill (I don’t do well trying hide how I’m feeling, which is why I loose when I play poker). My boss, after the meeting, pulls me aside and asks me if I was ok. Of course not realizing that my facial expression suggested otherwise I said, “I’m fine.” He then tells me how valuable I am and that I could not be replaced. “Don’t worry,” he says, “Your position is secure. With your ‘Can Do’ attitude, you will have no problems here.”
Let me explain why I was upset. I didn’t care that he was getting let go (I know I am a heartless bastard), I was worried about getting stuck with his work.
So now my ‘Can Do’ attitude got me so buried in work that I can barely keep up with my normal day to day functions. Where did I go wrong?