Ah, yes, this. When I went back to university after taking a break a couple of years ago I promised myself it would be out of pure interest, because I cared about the subject, not to get good grades. Of course it didn't work out exactly that way, pretty soon there's an assignment to hand in tomorrow, and exam to get points on next week... and again I found myself preparing to answer the questions I knew I was going to get, rather than delving into that one subject that seemed interesting, or reading through the proof of a theorem being used. The grades were good, the learning... maybe not so much.
Right now I'm working on my final thesis research, and I found a good subject. Everyone keeps asking what my deadline is, when it is going to be done, how I'm progressing. I don't care. I'm learning, creating and having fun. I want to be able to spend the whole day exploring a topic I don't understand, or refactoring parts of my simulation code that I don't like. I know I'll get it done at some point, and when I do it'll be a valuable contribution at least to myself and hopefully the field I'll be publishing in. That's what learning's supposed to be like for me.