So he went back to his offseason home in Tampa and ran.
This despite moving from the hot, humid climate he experienced during training camp with the Tampa Bay Buccaneers the past four seasons to the more temperate Midwest, where temperatures have rarely cracked 85 degrees over the past week during Lions workouts.
The extra training had nothing to do with the weather, though. It had to do with how the Lions plan on deploying Spence -- similar to how the franchise has used their other tackles since defensive coordinator Teryl Austin arrived in Detroit in 2014.
"Man, honestly, I just had to run a lot more," Spence said. "When I got here in OTAs, I mean, I know a lot of coaches say run to the ball, but I didn't know they meant run to the ball, you know, going 80 yards and running back to the line.
"So that was the main thing."
To prep for this, Spence said he worked out four days a week -- and ran four days a week. Beyond the typical burst work to increase his speed getting off the ball, Spence went for longer runs, at least longer in the context of defensive linemen on a football field.
A typical day left Spence running 10 50-yard dashes interspersed with his burst work. His weight remained at 305 pounds, which is what both he and the Lions wanted.
"Just keep my heart rate up, keep my conditioning up," Spence said. "In this game, you've got to be able to go, man. You've got to be able to go."
It helped Spence adjust fast to Detroit's system, something that is surprising. Other players, when they have come in the past few years, have said it has taken months to adjust. Even Haloti Ngata, who entered the system in 2015, said it took him a while to pick up the nuance of what Detroit likes to do on the interior of the line and the concept of attacking first versus reading blocks and reacting.
"I have no idea how he's done it. He's been amazing," Ngata said. "Him and [Jordan] Hill, they've picked it up so fast and the thing is, I think they kind of just bought in faster. They bought into the system, bought into what we wanted them to do and they just took off with it.
"For me, my first year here, it took me a little while to even get it. To see them get it so fast, it's amazing."
Spence knows there will be more of a rotation of linemen in Detroit than in other places around the league. The Lions rotate their defensive linemen similar to line shifts in hockey or lacrosse, where guys will get a certain amount of plays before coming out based on either rotation or scheme situation.
It allows a player to be more aggressive and "go all out for four plays" before subbing out as part of the rotation. It is a freeing proposition. It's also why he started his longer -- for linemen -- and more intense runs.
Spence seemed stunned other defensive tackles in years past struggled learning the scheme, saying "Oh wow," when he was told that Monday. He credited playing under Lovie Smith in Tampa as part of the reason he believes he was able to adapt so fast and that it was part of the decision-making process when he came to Detroit.
He spoke with defensive line coach Kris Kocurek and did research about how the Lions tackles played. He watched the tandem of Ndamukong Suh and Nick Fairley when they were the interior of the Lions line in 2014 and saw the productivity.
"I was looking at that and talking to coach Kris before I was making my decision, he told me he was going to give me that opportunity," Spence said. "You know what I'm saying, just to be free, play in people's backfields.
"You know, most coaches say that and then when you get here, they want you to read, playing blocks. But he kept his word."
Now it's up to Spence to live up to his part of it by producing when games begin to matter in September.