Carrie Underwood, like many new mothers, says she found it difficult to "bounce back" after having her second child.

The singer's son Jacob Bryan was born in January of this year.

"After having my first kid [Isaiah, 4], I felt like I bounced back fast. And then with Jake, it was like my body took a minute to get back to me. It was frustrating, because I’m like, ‘Why wasn’t it like the first time?’" Underwood reveals to People.

However, the superstar has learned how to "be kind to yourself" in the years since having Isaiah, saying, "But I’m four years older. That also helped me shift my mindset — I’m still working hard, wanting to be the best me possible, but cutting myself slack and just thinking, ‘Be kind to yourself.’"

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"It’s amazing what we [women] do to ourselves," she adds. "We’re probably all our toughest critics."

Flash Back to When Carrie Had Baby Jacob:

Underwood also shares that she doesn't believe "cheat days" should be part of a modern mom's vocabulary — just enjoy life! The "Drinking Alone" singer acknowledges that holidays can be stressful, balancing health and fitness with the other factors of life. So, how does Underwood deal with that?

"You can just say, ‘I’m going to enjoy myself on the holidays,'" she says.

"It’s all about friends and family and food and parties, and indulging responsibly,” she adds. “And when New Year’s is over, get back on the horse. It’s like, ‘Okay, I’ve had my holiday fun. Now it’s time to get back on my path.'"

Carrie Underwood's Post-'American Idol' House Is So Modest!