If Rick Nash has seemed quicker on and to the puck, more involved in the action below the goal line and in front of the net, and simply in better condition these first few days of training camp than he was throughout last season, that’s because he is in better shape.

Both physically and mentally.

“For sure, the staff wanted me to get in better shape over the summer and that was my objective coming into camp,” Nash told The Post after Sunday’s scrimmage. “I did a lot of work on cardio, a lot of running and track work. I can feel the difference. I feel great.

“You know, I was in pretty good shape at the start of last year, I felt really good those first two games in Phoenix and LA, but then I got injured the next game in San Jose and missed the next six weeks,” said No. 61, who will not be in the lineup for Monday’s preseason opener against the Devils at the Garden. “That definitely made it a little bit tougher the rest of the way.”

Nash missed six weeks and 17 games with the concussion he sustained on a head shot from Sharks defenseman Brad Stuart. It was Nash’s second concussion within 10 months as a Ranger, the first courtesy of Boston’s Milan Lucic in February 2013. And the second one changed Nash’s game, turning him into less of a physical player and more of a perimeter one; less effective, to be sure.

Night after night, Nash criticized himself for “not getting to the inside.” The winger — who did lead the Rangers with 26 goals — was credited with just 11 hits in 65 games after having recorded 453 hits in 385 games over the previous five seasons.

But even when the flesh was willing, well …

“Coming back from the concussion, it was tough for me to feel comfortable on the physical side of it,” Nash said. “You can say maybe I was a little ‘careful,’ but it wasn’t as much being ‘careful’ as just not being comfortable in certain situations.

“When you come back from a knee injury, you might not be immediately comfortable on cross-overs, or if you have a groin pull, you can’t shift on the edge to gain speed when you come back. You don’t feel comfortable doing those things that always come naturally.

“Coming back from a concussion, you want to get hit and prove to yourself that you can handle everything of that nature, but that’s hard to do in practices. It was different for me.”

Nash likely will open the season on a different side and with different linemates than he finished last year. Instead of playing on the right with Chris Kreider and Derek Stepan, Nash is expected to open on the left with Derick Brassard and Mats Zuccarello and fill the hole created by Benoit Pouliot’s free-agent defection to Edmonton.

He will be expected to get in on the forecheck and be a physical presence on that unit — the same type of presence he was in an otherwise fallow postseason, during which he recorded 45 hits in 25 playoff games, if only three goals.

“I was a lot more physical in the playoffs,” Nash said. “I was able to get to the inside. But that comes with confidence.

“I’m feeling good now. Whatever role they have for me, I’m good with it. I’m really looking forward to it, too. It feels great to be back.”

Derek Stepan, who did not participate in the scrimmage, is “day-to-day” with what the Rangers are calling a “foot contusion” in the aftermath of blocking a shot during one of last week’s pre-camp, informal workouts. Stepan underwent X-rays on Saturday that came back negative.

The Blueshirts’ “A” group will play against the Devils. The roster will feature Henrik Lundqvist, Kreider, Kevin Hayes, Martin St. Louis, Matt Lombardi, J.T. Miller, Marc Staal, Dan Boyle, Ryan Malone, Mike Kostka and Matt Hunwick. The “B” group including Nash, Brassard, Zuccarello, Anthony Duclair, Ryan Haggerty, Marek Hrivik and Cam Talbot will form the roster for Friday’s match in Chicago.

Coach Alain Vigneault cited Miller and Haggerty for their strong work in the scrimmage, while also praising Hrivik.

Regarding the battle for the spot as seventh defenseman that appears to be between lefty Hunwick and righty Kostka, Vigneault said: “[Side] doesn’t matter. I’m looking for a guy who can help us in our transition game. If I can find a defenseman like that, I’d like him to be our seventh guy.”