“Attitude is contagious,” Chris Pratt told HuffPost Entertainment during a recent interview. “All the time.”

At the moment, Pratt’s attitude is one of absolute joy. Just in the last few days, the 35-year-old has watched the Brickyard 400 from Tony Stewart’s pit box (“UN F***ING REAL!!!” Pratt wrote on Twitter), rang the bell at the New York Stock Exchange, surprised a group of New York City students at a movie theater and appeared with David Letterman on “The Late Show.” His energy in boundless, and it’s all because of “Guardians of the Galaxy.”

“I don’t have a lot of experience running around and promoting a movie in which I’m the lead, so I feel like I’m getting spoiled right off the bat,” Pratt said of the latest entry in the Marvel Cinematic Universe. “I don’t know what I’ll do if I’m ever in a movie that I hate. But so far, people just genuinely like the movie.”

There’s a reason for all that “Guardians of the Galaxy” goodwill: It’s great, at once a throwback to “Raiders of the Lost Ark,” “Star Wars” and other adventure movies that men and women in Pratt’s age group loved as kids, and also a leap forward for the increasingly homogenized superhero genre. Directed by James Gunn, “Guardians of the Galaxy” is cool and shaggy and funny and heartfelt and weird; a key moment in the third act hinges on an impromptu dance. Pratt is a big reason why it all works: He stars as Peter Quill, the leader of the ragtag Guardians of the Galaxy, and steps up with a performance that recalls the best elements of Harrison Ford, Tom Hanks, Tom Cruise and Andy Dwyer, Pratt’s “Parks and Recreation” alter ego. (“I’ve seen the future of male movie stars,” Pratt’s “Parks and Recreation” co-star Rob Lowe wrote recently on Twitter, “and its name is Andy Dwyer.”)

Ahead of the release of “Guardians of the Galaxy,” Pratt spoke to HuffPost Entertainment about his fears that the project would fail, his hopes for a sequel and the time he entered a dance contest on a cruise ship.

“Guardians of the Galaxy” was a risky idea for Marvel, but the end result is perhaps the studio’s best movie yet. When did you realize it had worked?
About three weeks ago, when I saw the film. Leading up to that, I had been having nightmares that it was terrible. In London, during production, I had a hunch we were doing something special, but you don’t know if you’re deluding yourself by having those feelings. You have to lower your expectations so that you’re not heartbroken if the movie comes out different. The truth is you just can’t tell if it’s going to be good. There are just so many steps that follow wrapping principle photography. All the music, all the animation — especially in a movie like this, when there are two characters who aren’t even there — all of the worlds, the way they look and the way the movie flows together. Especially when it shifts through tones like this, where it’s funny in one minute and very dramatic the next minute. That’s a difficult balance to find in the post-production process. In the course of the filming, I was worried. I didn’t know if it was going to be as good as it is. I was just so relieved when I saw it. I loved it. I could tell it was very, very special.

During production, were you at least able to tell that what you were doing was great?
No [laughs]. I wish I did. I had a feeling that some of it was really working, but you just don’t know. That’s the truth. Seeing the movie now, I am very proud of the performance and the way that it all came together. That’s the result of a lot of embarrassing failure on set. You have to wade through moments that don’t work, and trust that your director and your editor really want to make your performance work. I was really doing a lot of different things. I was just trying a lot of different things and really learning on this job. In the grand scheme of things, I’m still very new to this. Luckily, they captured enough good stuff and were able to find it in the edit to make it a complete performance. Maybe one day I’ll be able to know I did a great job while I’m on set, but I’m not there yet. I was still just really embarrassed and full of anxiety that I was blowing it the whole time.

But that freedom to fail has to be liberating for you as an actor, right?
Yeah, I don’t think that’s how they prefer to work. If you miss, you have to shoot again. You hope that the adjustments you make will allow you to hit a bullseye next time. There were a lot of times where it was six, seven, 10 takes in, and James was like, “This is not working.” So we were really finding it together. Maybe I’m giving away secrets here, but this stuff is not easy. You want it to be easy, but it’s not.

This is an old cliche, but it’s true: The more effortless something looks, the more effort it probably took to achieve.
There was a lot of working. There was one particular day where we did the “12 percent” scene. It’s about a seven- or eight-page scene. We had 10 and a half hours of footage for that scene. It’s a seven-minute scene. I was chopping away for 10 and a half hours before that tree fell. You know what I mean? If you cut it together, you can make it look like I cut the tree down in one swing. But that took a lot of time.

You have a couple of dance numbers in this movie. How much time and preparation went into those scenes?
There was definitely some homework that went into it. The character and myself are very similar in terms of who we were as kids. We’re the same age and from the same era. Literally born the same year. Everything I know about this character, I took from everything I was when I was 9. In terms of dancing, I loved Michael Jackson, some “Saturday Night Fever,” a little early hip-hop. I was the guy who would enter a dance contest in eighth grade and just do the Running Man for 20 minutes. And I’d get a solid third place. In fact, my brother and I both entered a dance contest as kids on a cruise ship, and we got third place out of four groups.

That’s good!
Yeah, pretty cool. We didn’t come in last. I just feel bad for the people who got fourth place and lost to two 12-year-olds who did the Running Man for the entire duration of “Everybody Dance Now.”

Well now they can say they lost to the star of “Guardians of the Galaxy.”
[Laughs] Yeah, that’s right. I have a feeling their relationship is already over. It’s too late.

You and James announced “Guardians of the Galaxy 2″ at Comic-Con. Have you given any thought to where you want that film to go?
Honestly, I don’t think a second goes by where part of me is not thinking about it. We’ve had a lot of conversations. The galaxy that has been opened up here is very, very rich. These characters are rich. We have more origins we can get into with all of the characters in “Guardians of the Galaxy.” There are several incarnations of the Guardians of the Galaxy in the comics, so I’m hoping we can see one or two new characters or different characters who we haven’t met yet. There’s obviously the potential crossover to the “Avengers” characters, but if it were up to me, I’d like to leave it in space and explore the universe that really only the truest Marvel fans have ever even heard about. Just open up this epic space opera again. I’d like to avoid bringing it to Earth. I think that’s what makes “Guardians of the Galaxy” so special.

This interview has been edited and condensed.