David Cobb was packing up his apartment this month, a senior sorting through memories, when he came across a letter his mother wrote him when he first got to college.

The record-setting Gophers running back has kept that letter pinned to his bedroom wall, alongside posters of Muhammad Ali, Jackie Robinson and Martin Luther King Jr.

"Good morning David," the letter starts. "We have been waiting a long time to watch you grow into the young man that you are. … Mom and Dad are proud of you! Always seek God first and call us! We are here no matter what!"

Nina Cobb's letter goes on to remind him of things she preached to him every day, while he was growing up in Killeen, Texas: No drugs, no drinking, no texting and driving.

"Be careful who you call friend. … Just think first before you act!" she writes. "We can't wait to see the great things that you will do over the next couple years."

Cobb got such a kick out of reading that again this month, he took a picture of the letter and posted it on Instagram.

Like usual, Mom had it right. Cobb spent two frustrating years waiting for his chance, but once he got it, he turned into one of the best running backs in Gophers history. He will cap his college career New Year's Day when the Gophers play Missouri in the Citrus Bowl in Orlando.

Cobb just earned his degree in sports management. Soon he will be off to the NFL, with CBSSports.com projecting him as a potential third-round draft pick.

Asked about the pride she feels, Nina Cobb said: "It's not just about the football field. It's about our son becoming a man."

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The text messages often arrive before 6 a.m. They are for inspiration. They are reminders to keep in line.

Nina Cobb sends these short missives to all three sons, and sometimes she will send them to her nephew, Gophers linebacker Damien Wilson.

For example, she will write: "Do something good every day. Do it when no one's looking."

Wilson and Cobb are cousins and have been roommates the past two years. Sometimes they will wake to find these pre-dawn text messages and just smile and roll their eyes.

But this November, a reporter saw Cobb walking in Dinkytown. The running back came upon a homeless man. Unaware anyone was watching, Cobb reached into his pocket for some money. The man took it and ran across the street to McDonald's.

"David's not a perfect kid," Nina Cobb said. "They're going to make mistakes. But I believe parents have to breed things into them."

Cobb's father, Caesar, is a retired Army lieutenant and a former professor of military science at Alcorn State University. Nina works as a nurse and watched over their three sons when Caesar was stationed overseas.

"She never misses a game," Cobb said. "She's just great to have, and not just for me and my two brothers, but for Damien and all my cousins. She's just always been there for us."

Cobb continues to heed her lessons. When he strained his left hamstring on a touchdown run at Nebraska on Nov. 22, it was the kind of injury that can deflate a whole team. But Cobb looked as pumped as anybody on the sideline when backup tailbacks Donnell Kirkwood and Rodrick Williams helped the Gophers pull off a come-from-behind win.

"[Cobb] was the first one out on the field when Rodrick scored," Kirkwood said. "He beat me, and he's got a pulled hamstring. It's just the type of guy he is. He's just a general good dude."

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Cobb is the first to admit he wasn't the happiest individual his first two years at Minnesota. He rushed for nearly 3,000 yards at Ellison High School in Killeen, before coming aboard as a late addition to Jerry Kill's first recruiting class with the Gophers.

Cobb had 10 carries for 57 yards as a true freshman, but a hamstring injury robbed him of more playing time. He was fully healthy as a sophomore but got just one carry for 8 yards.

He gave serious thought to transferring but credits Nate Griffin, the Gophers' offensive quality control assistant, for helping convince him to stay. Cobb said countless other players have come to that same crossroads.

"I was just lucky enough to have [Griffin] to keep motivating me," Cobb said. "He told me, 'Keep working. It's not supposed to be easy.' "

Those words echo something Nina has been telling her sons and nephews for years: "Work will win when wishing won't." She wrote those words on a banner that hung from the stands at all of Cobb's high school games.

Cobb was far from a finished product. He could break tackles and had extraordinary vision, but one area he struggled was pass protection. He continued working as a junior and rushed for 1,202 yards, even though he didn't get his first start until the season's seventh game. This year, Cobb broke Laurence Maroney's single-season school rushing record of 1,464, set in 2005.

Cobb has 1,545 yards heading into his final game. With his hamstring injury healed, he said he feels as good physically as he did before the season. He will be facing a Missouri defense that ranks 30th in the nation against the run.

When he's done, he will have a lasting legacy. Whenever Kill has a player seething over a lack of playing time, the coach can point to Cobb's story of patience and perseverance.

"I worked him hard early and stayed on him," Kill said. "And I think he understands now why."