...my grades were OK but not great. I did not care that much. I was shocked when I graduated with honors. I was like, "How did I do that?" I was not really trying to.

I felt a little guilty then. I often think if I had only applied myself I guess I could have graduated at the top?
I felt the same way during my university graduation. Everyone was all excited about having such a great accomplishment, and patting themselves for overcoming great difficulties, while I felt that there was nothing special about it. I just did what I was told to, one step at a time, and graduation was just another in a long series of steps. It's like, "anyone can do this, if they just went out and did it. What's the big deal?"
Master's level graduation was a bit different. They REALLY tax your brain and make you work in those classes.