The actor turned out for Dodgers pitcher Clayton Kershaw's Fifth Annual Ping Pong 4 Purpose Celebrity Tournament at Dodger Stadium in Los Angeles on Thursday, where he spoke with ET's Lauren Zima about the upcoming, and highly secretive, season.
"A lot of it is familiar... When you watch it, you're going to laugh, you're going to cry, [but] we dig a little deeper into these characters," Hartley shared. "Now that we already know them from season one, we're already invested in them, we don't have to spend time trying to let you sort of get to know who they are so that you could be interested in them. We already have an audience."
Recently it was announced that NBC had renewed This Is Us for both season two and three, which Hartley said gives the writers room to "get deeper into these characters quicker, because they know that they have a place to go and we have some time to tell these stories."
The 40-year-old actor -- who stars as Kevin Pearson, son of Jack (Milo Ventimiglia) and Rebecca Pearson (Mandy Moore) -- revealed that he's already read the scripts for the first three episodes and they're "tearjerkers, right off the page."
"I don't know how they keep doing this, but I feel like they're getting better!" he said, referring to the acclaimed writing team. "I remember having that feeling last year and I thought, 'Well, this is gonna go away eventually.' And they're continuing into season two! So hats off to the writers, they're fantastic."
While Hartley has gotten to read the first few scripts, and says the show is currently in production on the second episode of the new season, he revealed that the writers keep a lot of the storylines secret, even from the actors.
"I don't think it's for us, I think it's mostly just so that it doesn't get out, because there's so many like, top secret storylines," Hartley explained. "I always tell people this, when they say, 'What's gonna happen here? What's gonna happen here?' I always tell people, 'You think you want to know, but you really don't. You want to experience the event as it happens on TV.'"
"I think it's just to protect all of us, including the actors," he added.
The star said the recognition has encouraged him, his co-stars and the creators to think, "'OK, now, let's live up to that and lets go to work.'"
"It's fun. It's good to be recognized though, isn't it? [To be nominated] by your peers and stuff. I mean, that's awfully nice," he added.
If being on a hit show wasn't enough sunshine in his life, Hartley is also happily engaged to actress Chrishell Stause, and he's gearing up for their future wedding, which he said will include a "special" role for his 13-year-old daughter, Isabella, who accompanied him to Thursday's event.
"It's coming up real soon," Hartley said. "We're in the midst of planning, we're actually sort of closing up all of the planning situation now."
This Is Us season two premieres Sept. 26 at 9 p.m. ET/PT on NBC