Two years ago, Kelly Preston was struggling to make sense of the sudden death of her 16-year-old son Jett, who lost his life due to a seizure in January 2009.

The actress, now 48, credits her religion for getting her through the toughest period of her life. "To be honest, [it was] the Scientology Center," Preston tells Health magazine's September issue. "I don't know if I would have made it through without it."

(Preston and her husband, John Travolta, have been Scientologists for more than two decades.)

The experience taught Preston a valuable lesson. "Don't sweat the small things. Love your kids like it could be the last moment."

After a painful two years, the family (including daughter Ella Bleu, 11) finally received some happy news when baby Benjamin Hunter Kaleo was born in November 2010.

"We [had been trying] for quite a few years," Preston tells Health. "When I found out I was pregnant, I was floored. I'd snuck out of bed and then came back and woke Johnny up in bed. We both started crying. It was wonderful."

Motherhood, Preston says, is the single most important role she's ever tackled. "I've always wanted to be a mother, ever since I was 11. I was doing commercials for thousands of dollars, but I'd still babysit for $3 an hour just because I loved it."