Peterson, recovering from December knee surgery, was activated off the physically unable to perform list and was back practicing with Minnesota's first-team offense Sunday at training camp.
"I was like in a candy store today when I came out here and they threw me out there with the first group, just smiling," Peterson said. "I had to kind of calm myself down. I was going a little too fast for a walk-through in the beginning. For me, it's just so satisfying. I had a lot of people doubting me. A lot of people say this, a lot of people say that, but I kept my faith and kept working hard. Now I'm back in the mix. I can't complain."
After meeting with team doctors, coach Leslie Frazier and general manager Rick Spielman agreed to let Peterson return to practice, another big step in his recovery from left knee surgery. But Frazier preached caution with Peterson, saying activating him off the PUP list was just the next step in the process and doesn't mean Peterson is going to be let loose in any particular game.
Peterson tore his anterior cruciate and medial collateral ligaments in a game at Washington on Dec. 24 and had surgery a week later. But less than eight months later, he is back in the offensive huddle for the Vikings and will be back in pads on Tuesday.
"He's just special in so many ways," Frazier said. "We all know the severity of the injury and what's required to come back. But in his case, to see the steps that were taken along the way and how each hurdle that was put before him, he always met the challenge throughout this rehab. So this is the next step. (I'm) looking forward to seeing how he responds, and I think we all are. We'll just take it day to day and see where he is."
Since he started training camp on the PUP list, Peterson can start practicing, but must be held out of contact for two days before he's able to practice in pads in the afternoon for Minnesota. Because of the rules within the collective bargaining agreement, players returning are required to have a two-day acclimation period where they can't practice in pads. The Vikings training camp involves a walk-through in the morning with a padded practice in the afternoon.
Peterson had his sights set on being ready for the Sept. 9 season-opener since undergoing surgery and has pushed through an intense rehabilitation and is on the cusp of meeting his goal. Known as a tireless worker, he's been rehabbing intensely on the side fields at Minnesota State University in Mankato, site of Minnesota's training camp. He's run stairs in the adjacent stadium and also started to practice football activities under the watchful eye of head athletic trainer Eric Sugarman.
Peterson said he expected to be activated soon after talking with Frazier last week and while the team traveled to San Francisco for the first preseason game Peterson was preparing.
"We kind of had a conversation before they left to go to San Fran and I've just been getting my mind right all weekend," Peterson said.
When he was finally told he would be activated, Peterson couldn't help reflecting back on the months of rehabilitation, calling it a "true test." He said the toughest part was regaining the strength in his left leg and increasing the range of motion in the surgically-repaired knee.
After all the work, the team decided Peterson has accomplished everything he can working by himself on the side.
"Pretty much what it came to is I did all I can do as far as training and working hard, doing different drills," Peterson said. "It was time to get back in the mix and start doing some football activities. That's the next step. I'm feeling good. I feel like I'll be able to go out and participate in everything. But I'm going to let these guys do their job and I'm just going to go with the flow."
Peterson had been making comments to Frazier during the opening two weeks of camp, saying he's ready to be activated. But Minnesota has had to slow down one of their top offensive playmakers, who they made the highest-paid running back in the league last preseason.
"He can be a good politician," Frazier said. "He did a good job of lobbying. But it wasn't his lobbying that got us to this point. It was his work, the things he's done up to this point in his rehab. So you have to credit him with the hard work that he's put in with our trainers, with our strength coaches, and he's done a great job to the point where they feel like this is the next step."
Frazier even gave Peterson the chance to pull back before joining his teammates for Sunday's walk-through, but Peterson wasn't having any part of taking it easy now.
"I told him this morning, 'Now's your chance to say, Coach I was wrong. I don't think I'm ready,'" Frazier said. "He said, 'I'm not saying that. I'm ready. I can't wait to get out there.' So, he's pretty excited."
Peterson finished with 970 yards rushing and 12 touchdowns in 12 games last season, but missed three games with a high ankle sprain and missed the final regular season game after getting hurt at Washington.
Peterson, who missed reaching 1,000 yards last season for the first time in his five-year career, said the biggest step is reacting to game situations and taking the first hit. Peterson, who said he doesn't plan on wearing a brace this season and will likely have a sleeve for his knee, feels taking a hit and being tackled is the final step in his return. And he doesn't feel there is a way in practice to replicate the feel of getting hit in a game.
"I don't think there's a way you can do it," Peterson said last week. "You got to get hit in order to get that full effect. Hopefully we come out here and get some live periods going on and I'm sure everything will be high, but it will at least be a little something."
Frazier made it clear he doesn't want Peterson taking any hits from his teammates though.
"I don't think there's going to be a time when we say 'It's live on Adrian,'" Frazier said. "It wasn't that way before. You don't want him going to the ground in practice. The first time he'll go to the ground, if I have anything to say about it, will be in a game situation. We're not going to take him to the ground in practice."
Frazier is optimistic about Peterson's progress since surgery, but added a cautious tone to the announcement.
"I want to caution you," Frazier said. "I know there are a lot of fans that are very optimistic and are excited about seeing him back, but for us it's just a part of the process. It doesn't mean a whole lot other than he's done a great job in his rehab up to this point; off to the side with our strength coaches, with Eric Sugarman and his staff. And our medical staff explained to myself and (general manager Rick Spielman) the next step for him in the process is to get integrated with his teammates. That's just what it means. He's done everything he can do on the side. It doesn't mean in the future he's going to be lining up with our team in the opening game. We don't know that. We have a long time to determine that. This is just another step in the process."
Before making Peterson active for the first regular season game, Frazier has said he'd like to see Peterson in a preseason game first. Frazier said Sunday he still wasn't sure when Peterson might be ready for game action.
"Daily we'll gauge where he is," Frazier said. "If it looks like that's the next step, we'd want to do it. If we could get him in a game and get a little bit of a taste of NFL action in a live situation, that would be good. But we'll see."