Carrie Underwood Got 'Emotional' Recording Christmas Duet with Son Isaiah: 'I Was Crying'

Carrie Underwood has performed duets with some of music's biggest stars but it was her 5½-year-old son Isaiah that left a lasting impression!

The country star and her son teamed up to sing "Little Drummer Boy" on Underwood's first-ever holiday album, My Gift, which she released in September.

"It was so great," the singer tells PEOPLE in this week's issue. "When we recorded, I was able to be in the booth with him and encourage him and try to remind him what words were coming up next, things like that."

Underwood, 37, reveals the most emotional part for her was hearing Isaiah's part after the studio session.

"I got to listen to his vocals [get] put together and then listening to myself with him," she says. "I was laughing, and I was crying, and it was just very overwhelming in a good way. It's just very emotional."

Now performing in her own Christmas music special on HBO Max, which includes renditions of holiday classics and originals from her album, Underwood says making both was exactly what she needed this year during the coronavirus pandemic.

"It really was a gift for me. It was a welcome distraction," she says. "It was such a stressful, hard year and nobody knew where it was headed the majority of the time. It was nice to be able to go in and have this to look forward to."

One big silver lining for the singer was being able to spend more time with her family including her younger son, 23-month-old Jacob, and her husband Mike Fisher, 40.

"I tried my best to start every morning just being thankful," she adds. "We're all healthy right now. And we have each other, and I got to just stay in one place, which hasn't happened in a long time and really just watch, especially my youngest one, to get to know him and kind of watch him grow."

As for what she's learned about herself, Underwood insists she "definitely discovered that I can go with the flow a little more than I thought.

"Once we were presented with challenge after challenge, instead of lamenting or freaking out, we came to expect that things weren’t going to go as planned," she says. "Once we embraced that, we were able to say, 'Okay, now what? How do we overcome obstacles?' It turns out we’re pretty good obstacle-overcomers."

Underwood hopes that her holiday special will allow people the time to sit down with their families and watch together.

"Even through a difficult year, I hope it gives people a sense of peace," she says. "And makes them smile — and sing along."

My Gift: A Christmas Special from Carrie Underwood starts streaming Thursday on HBO Max.

For more from Carrie Underwood, pick up this week's issue of PEOPLE, on newsstands everywhere Friday.