During the sit-down chat, the brothers revealed that they actually went to therapy together for a year prior to their professional reunion.
"We literally spent a year basically doing therapy, working through some things and figuring out what this chapter would look like," Nick explained. "We've had to be really open and honest. There are things in the past that bothered us from time to time, even in our performances that we would do."
Nick then went into detail about how the idea for them to reunite first came to be.
"About a year and a half ago, we started filming a documentary… [that] tracks kind of our childhood into our time in the band, and it was gonna be a story about where we are today," Nick shared. "With separate lives, doing separate things -- Joe with DNCE, me with my solo stuff."
"But during [filming and production], we started to realize that there was a magic that we felt like we were missing," he continued. "So the process was basically just [us saying], 'Why don't we give this another shot?'"
"So we started playing a little music together and realized right away this is where we're meant to be in our lives at this moment," he added, to the roaring and supportive cheering of the crowd.
Later in the show, Corden challenged the siblings to a fun game of "Spill Your Guts or Fill Your Guts," where they had to either answer a question or eat the nasty food in front of them, which included plates of things like "beetle marmalade toast" and "worm spaghetti."
Corden awkwardly asked the guys everything from "If you had to buy a Nick Jonas album or a DNCE album, which one would you buy?" to "Name the most famous person who's hit on you."
However, the brothers' heartwarming backstory behind their decision to get the band back together is a far cry from the hilarious explanation Corden gave in a pretaped intro to Monday's show.
As seen in the short intro, Corden and his bandleader, Reggie Watts, depressed at the state of the world and the stream of bummer news stories, longs to return to the good old days of 2013, when the world was a simpler place and the Jonas Brothers were the musical champions of all things good and wholesome.
In an effort to save the world, Corden and Watts travel the nation in search of the three members and then forcibly kidnap them, tie them to a chair and demand that they reunite.
While it may not be the real story behind the band's reunion, we can all hold out hope that the Jonas Brothers might bring a sense of harmony back to the world.