I'd say of most of the folks I've asked that question, without fail, that is the most common answer. A few times people have said they wished they would have been more present and really enjoyed each day more. For me personally, I would answer the much the same as you. I wished I would have taken it more seriously, and put out more effort. In the end, however, I found that in the long run it hasn't seemed to make much of a difference. I now find no one EVER asks what where my college marks. Its all about experience now. BUT! One has to gain that experience somehow haha. And the marks sometimes get you in the door. I wish you all the best!