Giants training camp started Thursday.

Giants football season starts Tuesday.

After three practices, countless meetings and nearly a week of being together, the players will wear full pads for the first time this season. It’s a milestone that coach Ben McAdoo circled on the camp calendar when the players first arrived, promising to make the Giants a physical team. And while safety dictates that there won’t be true game conditions — McAdoo said they won’t be tackling to the ground, at least not at this point — the players and coaches are looking forward to their first opportunity to have actual contact since the end of the 2015 season.

Hits gonna get real.

“Man, it’s always a good feeling to get into pads, shake the rust off and get to put your hands on somebody,” defensive end Olivier Vernon said. “There is no better feeling than that.”

“It’s what we do,” center Wes ton Richburg said of hitting. “I think that’s when you learn what kind of team you have. Once the pads come on, it’s real, it’s not us running around in our underwear. I think you can learn a lot about some young guys, see what guys can do when it actually is real.”

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There’s a lot to see. The rookies, of course, will be tested to see how they measure up. And the free agents such as Vernon and Janoris Jenkins and fullback Will Johnson will have their first chance to show the Giants what their investment looks like.

Johnson was so excited to be in full pads that he ditched his team-issued gym shorts for Sunday’s practice and wore his game pants (without the pads inserted in them).

“When the pads go on, you get to show the physicality side,” he said. “At my position, for my teammates and coaches, it gives them something to see from me, being new. It’s a day I’m looking forward to.”

Linebacker Devon Kennard said practicing in shorts and helmets can be “frustrating” for a defender who puts himself in position to make a tackle, then must olé the ballcarrier to avoid contact.

“You have the plays when you can’t wait until you get the pads on because you know what you could have done in that situation,” Kennard said. “We have to protect ourselves and each other, so I understand the concept.”

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Still, Kennard has found himself buzzing past an offensive player and thinking: Man, if we had pads on . . .

“I don’t really say it,” he said with a grin. “They’re my teammates. But in my head, definitely I’m thinking about it.”

Despite his reputation as a drill sergeant, Tom Coughlin’s training camps of recent years generally were light on physicality. The grind was more mental and the hitting was limited to “thuds,” mostly in the name of avoiding injuries.

Of course, Coughlin’s last few seasons with the Giants were light on wins, too. Getting back to hard hitting in practices is just one of the ways McAdoo seems to be shaking up Giants camp. And he has the blessings of the organization.

“You can’t be too soft, because then you develop a soft football team,” general manager Jerry Reese said. “You have to have calluses coming out . . . You have to come out of training camp with some calluses on you. That is what training camp is about.”

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It’s what football is about.

“One thing about this game is you have to be physical,” Vernon said. “You can’t be out there soft-pawing or anything like that, so I think that is the biggest thing come Tuesday — to see who wants to come and play.”

“The game looks a little different than it has in the past,” McAdoo said, “but at the end, the teams that are standing at the end are the physical teams and the heavy-handed, tough teams. The game may look a little bit different, but that part hasn’t changed and it never will.”