Nick Lachey: unplugged!

The cute crooner lets ET exclusively backstage at his private rehearsal for his upcoming tour!

Leaving headlines for his break-up with JESSICA SIMPSON behind, NICK LACHEY proves there's a lot left of him with an all-new tour, kicking off September 20. Our MARK STEINES is backstage with the singer at his private rehearsal hall in Los Angeles to get the scoop on his upcoming tour.

"I love being on tour," he says. "It's one of those rare experiences I've really missed from not doing it for five years."

When he's not driving the tour bus (something he says he's only done once), Nick spends most of his time on tour preparing for each show, either by drinking hot tea or warming up his voice. "It's like an athlete stretching his hamstrings," he says.

And with no gym in the bus, Nick says it's actually not difficult maintaining his hot bod. "An 80 to 90-minute show every night is great cardio," he reveals. "I sweat my tail off on stage."

The former 98 DEGREES member says it's quite a change to be performing solo. "It's a little intimidating when you're used to being on stage with three other guys," he says. "But I'm excited."

And he's ready for all the surprises that come with a live show. "As much as you prepare and plan ahead, there's no substitute for the live moments," he notes.

The tour runs until October 26. Nick will be singing the songs off of his What's Left of Me CD, which was a therapeutic album for Nick to make.

"Writing the album, recording the album," he says, "was a great way to channel my feelings and my frustrations."