Marcus Lattimore, the South Carolina running back whose career was ruined by a devastating knee injury two years ago, has given up his hope of playing in the NFL.

Lattimore, 23, made the announcement in a touching note on Twitter:

“After prayer and careful consideration, I have decided it’s time to end my professional football career. I have given my heart and soul to the game that I love and it’s time for me to move on to the next champter of my life and help others. I have given every ounce of my energy toward making a full recovery from my knee injury and I have made a lot of progress. Unfortunately, getting my knee fully back to the level the NFL demands has proven to be insurmountable.”

Lattimore was one of the players everyone was rooting for when he was taken by the San Francisco 49ers in the fourth round of the 2013 NFL draft. His injuries made him a longshot, but his talent was worth the risk for the Niners, who brought him along slowly and allowed him to train and work into shape. After tearing his left anterior cruciate and medial collateral ligaments in 2011, Lattimore tore three ligaments and dislocated his kneecap in 2012. After the second injury, he initially was told that he might not walk without assistance ever again, but he worked his way back.

“I am grateful for the entire 49ers organization,” Lattimore wrote. “Their decision to draft me was the realization of a lifelong dream to be an NFL player and I cannot thank them enough for believing in me and for doing everything in their power to assist in my recover. I will always be a 49er!

“Though I am proud of what I have accomplished throughout my football career, I am sincerely disappointed that it must end, but I trust that God has a great plan for my future, . As for what’s next, I will be returning to the University South Carolina to complete my degree. I cannot say enough about the support from the Gamecock family and I promise to always represent the garnet and black with honor and integrity. I will also continue to work with my foundation, the Marcus Lattimore Foundation / DREAMS, to provide opportunities and platforms to benefit youth sports programs in the state of South Carolina. I am looking forward to pursuing my personal interests and helping others achieve their goals and dreams.

“There are so many people who have supported me throughout my career, it is is impossible to list them all and to show them the proper gratitude. I must thank God for all of his blessings and guidance. I would not be where I am today without the support of my family. I also appreciate the outpouring of support from friends, fans, opposing players and strangers; your support means more than you will ever know.”

What comes next for Lattimore? He has a tax-free, $1.7 million insurance policy that he should be able to collect on, ESPN’s Darren Rovell reports.

And Steve Spurrier, his former college coach, says he has a place for him at South Carolina.