Chris Greenwood has practised with the Detroit Lions for the first time this month.
The cornerback sustained a hamstring injury during the third day of the team's training camp.
The 24-year-old told the Lions' website: "It's important. I'm just doing what I can, as much as they let me do, and what my body feels like. Just doing what I can.
"It's not frustrating. Just doing what I can, doing what my body allows me to do, doing what the trainers tell me to do."
Head coach Jim Schwartz added: "He's missed quite a bit of time. It's one thing being behind physically, but then also practices, technique, and things like that. He certainly has some ground to make up for sure."
Greenwood was drafted by the Lions last season, but did not play in 2012 because of an abdominal injury.
