ARLINGTON, Texas -- Jim Harbaugh went to unconventional lengths last week to help hammer home a point to his team.

The Michigan football coach read aloud a letter Friday he recently received from Anthony Riddle, a sergeant in the U.S. Marine Corps from Jackson.

Irked by what he was reading when it came to Michigan and its perceived youth, Riddle offered up his own two cents. And it apparently caught the attention of Harbaugh.

"This is in response to all the naysayers out there that think that Michigan football is too young, too inexperienced," Riddle wrote. "Your young men have worked their tails off in summer. They have battled each other for roster spots. They have battled each other for starting jobs. They have sweat and bled together.

"You tell your men that every down they play could be their last. Every down that they play, they'll never get that down back."

This is the letter @CoachJim4UM read to our team last night. #GoBlue pic.twitter.com/BlaWrDnGDP — Michigan Football (@UMichFootball) September 2, 2017

Harbaugh did -- he delivered the letter prior to Michigan's 33-17 win over the Florida Gators at AT&T Stadium. After the game, quarterback Wilton Speight referenced the two-page letter, unsolicited, when asked a question about the age gap in college football.

"He talked about in the letter how he was 18 years old and was fighting overseas," Speight said. "Just to hear that letter and say, 'OK, there's 18-19 year old guys going over there and defending our freedom, why can't we step out onto the field and play a simple game of football?"

The letter is timely because of Michigan's reliance on younger players this season. True freshman Tarik Black saw extended playing time in the game on Saturday, as did specialist Donovan Peoples-Jones and Ambry Thomas.

Meanwhile, sophomores like Rashan Gary and Chris Evans are both expected to be big parts at their respective positions.

"I get a lot of letters," Harbaugh said. "But there's been a few through the last couple years that I read to the team, and this was one of them. The message -- it's irrelevant what the age is.

"His Marines and what they did and what they sacrificed and they were able to do (is what matters). It's a group of guys in a unit or on a team that come together and do their job."

As you might imagine, Harbaugh hopes the letter might have a lasting impression for the rest of the season.