Nick Lachey spoke out for the first time this morning on "Good Morning America" about growing up with his brother Zac, who was diagnosed with Asperger syndrome, a form of autism, when Zac was 7.

"My family has dealt with that, and we're inspired by his courage and strength," the singer-songwriter said. "When you see firsthand how it affects the life of someone, my brother especially. He's been an inspiration to me, and I see how hard and challenging it is, and [I want to do] anything I can to help."

Lachey is now a paid spokesman for the Lindt Gold Bunny Celebrity Auction, which starts today and sells gold bunnies signed by celebrities like Blake Shelton, Celine Dion, George Stephanopoulos, Lucy Hale, Tom Hanks and more, including, of course, Lachey himself. All proceeds benefit Autism Speaks, an autism advocacy organization that sponsors autism research.

"The work they do in terms of research; there are so many questions where autism's concerned. One in 68 kids will now be diagnosed, and my younger brother Zac is one of those kids," Lachey said.

Additionally, 10 cents from every Lindt bunny sold between now and Easter will benefit the charity as well.

Nick Lachey with his brother Zac. (Courtesy Nick Lachey)

Lachey, 40, has been busy lately in addition to his autism advocacy. The singer has been balancing recent fatherhood, marriage and a new gig as host of VH1's "Big Morning Buzz Live."

"It's [fatherhood] more magical than I could have ever imagined. Every single day is a new milestone, a new moment. It's the best thing that's ever happened to me," he said.

Turns out one is not enough for dad Lachey, who said he and wife Vanessa Minnillo plan to give 2-year-old Cam a sibling soon.

"Yes, at some point we will definitely give him a sibling. We couldn't be happier," he gushed.

Lachey also plans to drop new music for his fans soon, confirming that he's working on a solo project.

"Absolutely," he said. "I'm back now in the studio working on another solo project."