Nick Jonas says he and his older brothers "spent a year doing therapy" before reuniting for their first music album in almost six years.
The 26-year-old singer admitted it took a while for them to "work through" the rift that had caused the band to split in 2013.
Speaking on The Late Late Show with James Corden, Nick said: "We literally spent a year basically doing therapy, working through some things, and figuring out what this chapter would look like. 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."
Now that their new single 'Sucker' is winning hearts all over the world, the brothers are set to star in an exclusive documentary for Amazon Prime Video that will give a "personal, behind-the-scene look" as the trio reunite for their upcoming tour.