AP

San Francisco running back Marcus Lattimore says he’s so fired up to get back on the field after the gruesome knee injury he suffered last season at South Carolina that he wants to go harder in offseason workouts than the 49ers will let him.

Lattimore told the Associated Press that the most difficult part of his first month as a member of the 49ers has been doctors and trainers slowing him down and urging him to be patient in recovery from reconstructive knee surgery so he doesn’t aggravate the injury and set himself back.

“I just want to train as hard as I can,” Lattimore said. “But I understand why they want me to slow down. . . . I want to have a long, healthy NFL career.”

The knee injury Lattimore suffered in October was so severe that there were fears it would end his football career, so it would be amazing if he plays this year at all. No matter how hard Lattimore wants to push himself, he should put his focus on gradually improving to get himself ready to play — probably in 2014.