What you have done since your undergraduate days is far more significant than how focused/motivated you were at that time. Everyone understands that students are still figuring out their priorities, and that adolescents are insane by definition.
If you're worried about it anyway, you may want to have an answer ready in case someone asks you about them. Mine would be a combination of:
-- I was spending too much time on student activities, mostly on volunteer projects though I admit D&D ate a great deal of my spare time as a freshman.
-- I was still figuring out what I wanted my actual career path to be. (In fact, my degree says EE but I've wound up returning to CS ... my grades would have been better if I'd stuck with my first love, but I felt I needed to balance my knowledge of software with more hardware insight.)
-- I was more concerned with learning the material than with proving I had learned the material. As a result, I tended to work hardest on homework in the classes where I was struggling, and sometimes blew off homework in classes where I felt I didn't need the practice. If you could look at my records in greater detail, you'd see a fair number of courses where my final grade was a B because my homework grade was C but I blew away the final. Obviously, I've gotten smarter about time management since then.
Note that every one of those, while true and admitting a failure, also acts as an opportunity to discuss what I learned from that failure, what strengths it demonstrates to offset the failure, and why I'm a good candidate now. Use it as an opportunity for storytelling and marketing; make lemonade out of the lemons.