The road to motherhood wasn’t an easy one for Mariah Carey, who says going through a miscarriage before she became pregnant with her twins was “really tough” and inspired her to change her lifestyle.

Carey says she became more Zen-like and used acupuncture to relax, and also underwent fertility treatments to try to get pregnant again.

“The main thing I did that was tough, was to go on progesterone like every month… and then when I was pregnant, I had to stay with the progesterone for 10 weeks,” she told Barbara Walters in an exclusive interview airing tonight on “20/20.” “It minimizes the chance of miscarriage by 50 percent.”

The treatment worked, and at age 40 Carey learned that she and husband Nick Cannon were expecting twins. Moroccan and Monroe are now six months old.

Carey’s happy marriage to Cannon is very different from her first marriage to record executive Tommy Mottola, the man who discovered her.  She said that experience made her “afraid of the concept of marriage.”

“But this is a different situation and … I’m a different person,” she said.  “It’s a different time in my life.  And nobody will ever be able to steal my spirit again.  So I’m just happy to be in love and to be here. ”

“When he’s nice, he’s the best guy in the world,” added Carey.

Both Carey and Cannon admit to being impulsive, marrying weeks after they started dating.  Cannon, 11 years younger, proposed to Carey in the Moroccan room of her home, which inspired their son’s name.

And the twins just might just take after their mother when it comes to their musical talents.

“They’re incredible,” Carey said.  “But I will say that they really respond to music.”

For his part, Cannon said he wants them to grow up to do something greater than entertainment. “I want to make sure we get education first,” he said.

“Society puts too much on entertainment and entertainers,” he said. “They praise them like they’re royalty, especially in America, where it should really be about the teachers or, you know, the doctors. I want them to be able to sing as beautifully as their mother.  I want them to be able to play instruments and everything.  But I want them like … ‘Go get a Ph.D’”

The twins are “our little geniuses,” he said.  ”They can do it all.”

“You can help them with their homework because I know I’m not going to know anything about it,” Carey joked.  “No.  I’ll make sure I get the tutor that knows, though.”

Watch Barbara Walters’ exclusive interview with Mariah Carey and husband Nick Cannon, plus see their babies’ faces for the first time, on “20/20? Friday at 10 p.m. ET.