And when the 2015 linebacker from Naperville Central visits Illinois, he feels like a member of the family.
"I'm not even a part of the Illinois football program and you can feel it," he said. "Just being around the coaches and players, you can feel the family. It's just there. The connection they have with each other is not just a connection of co-workers. It's a connection of fathers and sons and brothers. It's definitely real."
The 6-foot-2, 220-pound standout visited last weekend along with 22 other underclassmen. He's been on campus numerous times before, so he's been there done that. The tours and introductions have been done before, but McMillen said one portion of the visit was different. He got to sit in with the linebackers and Coach Mike Ward during position meetings.
"Oh, it was awesome. It's weird going and learning these defenses and everything like that," he said. "You're still in high school and you're like, 'wow, this is what a college defense is all about.' It's a good time.
"You think high school defense are complicated and everything like that. In college they have calls for literally everything. It's definitely going to be a big step in football knowledge and getting to the next level."
Ward is McMillen's primary recruiter.
"He's such a good guy. He's so straight forward," McMillen said. "He's not going to lie to your face. The neat thing about Coach Ward being my recruiting coach is he's the linebacker coach as well. Me being a linebacker, it's the best of both worlds."
And Ward isn't the only staff member that has McMillen's respect.
"Coach Banks is awesome, too," he said. "All the coaches at Illinois are just overall good men. They don't just preach football, they preach family. That's the most important thing."
"Illinois is definitely up there with my top schools," he said. "It's definitely cool there."