It wasn't long before his dream turned into a nightmare.
"We were in one-on-one drills and here I am, the second-round pick, feeling good about myself," Johnson recalled. "They match me up against this guy named Curtis Martin. He hadn't played his last year at Pitt, and it's my job to stick with him man-to-man. I just got torched."
That night, when he returned to his hotel room, an exhausted and devastated Johnson remembered calling his father. The first words out of his mouth were, "Dad, I don't know about this NFL thing."
As it turned out, Johnson would be just fine, and Martin, the team's third-round draft choice, regularly torched opposing linebackers en route to a Hall of Fame-caliber career.
If only Johnson had known that was how things would turn out, the 1995 rookie minicamp wouldn't have been so tense for him.
"You get there for the first time and you're nervous. You're entering the unknown," Johnson recalled.
"All of a sudden you're in the same locker room with guys you've watched on TV and the reality hits you that this is now your livelihood, and here you are in a new place. Until the final cut day, everyone is thinking about themselves and making the team, which in and of itself creates somewhat of an isolated, lonely existence.
"Think about it. What other job is there where you are graded on every little thing you do? Every practice rep is critiqued. Every drill. Every snap. It's a whole different level of pressure."
This is what members of the Patriots' 12-member draft class have to look forward to Friday when they step onto the Gillette Stadium practice field for the first time as professionals. They will be joined by eight rookie free agents and a handful of players in for tryouts.
In many ways, what will unfold is like a college orientation session as the rookies will be introduced to the Patriots' way of doing business.
From a football standpoint, they will take part in meetings and then apply what they learned in those meetings on the field in a practice that does not include full pads. The Patriots are scheduled for two practices apiece on Friday and Saturday, each going for about an hour.
Bill Belichick enters his 36th season as an NFL coach, but even as the senior member of the league's head-coaching fraternity, he annually seems energized by the back-to-basics nature of rookie minicamp.
There is also excitement in seeing the entire rookie class together for the first time, with the team's scouts who evaluated them lining the field and watching them in a pro setting.
"It's always good to get back on the field this time of year," Belichick said on the first day of 2009 rookie minicamp. "You have the young guys come in here that are eager beavers and really just want to try to soak everything up. It's kind of the ultimate contrast from the last game of the year, when you've been working with the guys for [months] on game plans and real sophisticated stuff. This is kind of the other end of the spectrum."
The focus of rookie minicamp is on fundamentals and, in Belichick's words from 2009, "some real basic things."
As for what can be gleaned from rookie minicamp, well, not much.
In 2006, fans might recall glowing reports about Florida receiver Chad Jackson, the team's second-round draft choice that year. Jackson looked impressive while catching passes in shorts and a T-shirt. His chiseled physique and off-the-charts athleticism contributed to the thinking that he could be a big-time contributor.
That never happened, which reinforced that the real football evaluation begins when players put on the pads in training camp.
At this time of year, it's mostly about learning something in the classroom and applying it on the field. Not the most exciting stuff, but as Belichick said last year, it's the first step in a long process.
For many of the rookies, like Johnson in 1995, it's a step they'll never forget.