''I wasn't physically fit. I was out of shape, I was pretty fat,'' he recalled. ''Coming out of high school, I was just thinking, `It's going to be nice to be on a team. Maybe I can play by my senior year.'''
Dunn adhered to steady diet, spent countless hours in the weight room and worked diligently on the field. As summer ended in his second year at Maryland, Dunn - then a redshirt freshman - was called into the office of coach Randy Edsall.
''I still remember the day I told him he was going to be on scholarship,'' Edsall said Tuesday. ''He had no idea. Just to see the look on his face, the surprise, the joy, it's great as a coach to do that and have those moments.''
The meeting was pretty special for Dunn, too.
''He told me I was going to be starting, and right after that he offered me a scholarship,'' Dunn said. ''I couldn't believe it. As soon as he told me, I called my parents to share the joy. They were ecstatic. It was a great moment.''
Dunn started nine games at right guard last year before moving to right tackle. The sophomore is now Maryland's starting left tackle, the most important position on the line.
With Dunn leading the way, Maryland rushed for 285 yards against James Madison last weekend in a 52-7 victory. He also provided quarterback C.J. Brown with enough time to throw for 111 yards and a score.
''He's been a big part of what we're trying to do on offense,'' Brown said. ''I have a lot of trust him. He's got my blind side. He's done a great job for us and is becoming more vocal as a leader. His understanding the offense and helping make calls just trickles down the line.''
Dunn was lightly recruited after an unspectacular career at Walt Whitman High in Maryland. When it came time to choose the next stage of his education he opted for Maryland over Lehigh.
It is a choice he likely will never regret.
''I had a chance to be a part of this, even if I might not play right away,'' Dunn said. ''It's 20 to 30 minutes from my home. It's a great academic school. Lehigh is also a great academic school, but having the opportunity to play football at Maryland or Lehigh, you've got to choose Maryland. I think I made the right decision.''
Nothing was handed to Dunn, now 6-foot-5 and 300 pounds after adding a half-inch and 40 pounds since his arrival in College Park.
''He's just a great young man. He's a really good student, a really good person,'' Edsall said. ''The growth he's made since he's been here from a strength standpoint, from a movement standpoint from a technique standpoint, he deserves all the credit we've been giving him.''
Dunn may be a starter now, but his attitude remains that of a walk-on.
''I think I've done a decent job so far. It's nowhere near I want to be,'' he said. ''There's plenty of room to get better. I'm happy where I am, but it's not a stopping point.''
Plenty of unwritten chapters remain in Dunn's feel-good story, but thus far it is an inspirational tale.
''He didn't worry that he was a walk-on, I didn't worry that he was a walk-on, the team didn't worry about it,'' Edsall said. ''It's a great lesson: If you take your ability and combine it with work ethic and make a commitment to being as good as you can be, then this is what can happen for you.''