“Justin was the most excited about weird cravings,” the 26-year-old model and first-time mom-to-be told PEOPLE in a chat surrounding her new ambassadorship with athletic brand Copper Fit, in which she also stars in the new fall and holiday ad campaigns.

“He kept being like, ‘I can’t wait for the pickle run in the middle of the night,’ ” she recalls. “I’m like, ‘Okay.’ But I haven’t had anything. I’m fine with all food.”

Upton also admits she “stopped working out for a month” at one point during her pregnancy, because she “was so tired and there was so much travel.”

“But I’ve been completely trying to stay healthy and work out through the pregnancy, and doing the best I can,” she tells PEOPLE. “It makes me feel better, honestly.”

“What I’m working toward is different,” Upton says. “Instead of working toward being super fit, I’m strengthening my pelvic [area] and doing a lot of hip thrusts, body-weight hip thrusts and lunges and squats to help with delivery and make it easier, hopefully. Fingers crossed.”

The mom-to-be knows the difficulties of getting to the gym every day, which is why she and her trainer Ben Bruno created a new at-home workout program called Strong4MeFitness.com. It’s a 30-minutes-a-day routine, using minimal equipment, spread out over five days: two cardio workouts and three weight-training ones.

“You can do it anywhere in your house. I’ve done it while pregnant,” Upton says.

In a Thursday interview with Extra, Upton revealed that she and Verlander, whom she wed in an ultra-posh wedding in Italy last November, are not finding out the 𝑠e𝑥 of their baby until delivery day.

“We’re going to wait. We’re going to be surprised,” she said.

But do they have a shortlist of names? “We thought of names but we’re both in denial,” Upton joked to Extra. “We’re both like, ‘That’s a good idea,’ and then just ignore the other [person].”