Carrie Underwood Admits It 'Took a Minute' to Get Back in Shape After Birth of Son Jacob

When Carrie Underwood gave birth to her second son, Jacob, in January, she expected to quickly get back in shape, much as she did with her oldest son, Isaiah, now 4 years old. When that didn't happen, Underwood became frustrated that she didn't see her hard work paying off as fast as it did after her first pregnancy, until she decided to give herself some grace.

"After having my first kid,
 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 told PEOPLE. "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.' It's amazing what we [women] do to ourselves. We're probably all our toughest critics."

In addition to working out regularly, Underwood also maintains a healthy vegetarian diet, although she will gladly indulge over the holidays.

"I don't like to call them 'cheat days' — you're just enjoying life," explained the singer. "I feel like holiday time can be stressful when it comes to health and fitness, but it doesn't have to be. You can just say, 'I'm going to enjoy myself on the holidays.'"

"It's all about friends and family and food and parties, and indulging responsibly," she continued. "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.' "

The Oklahoma native previously opened up about her struggles with getting back in shape, acknowledging that her expectations for herself, and her body, were too high.

"The first time around, with Isaiah, it was easier for me," she told TODAY. "I think that's just the way of it. So you kind of have unrealistic expectations about the second time. [You think] it's going to be just like the first time. And it wasn't. And I'm like, 'What is happening? What am I doing wrong?'"

Fortunately, the "Drinking Alone" singer soon realized she was setting herself up for disappointment, and altered her mentality.

"I stopped trying to be perfect immediately," Underwood revealed. "And I started putting one foot in front of the other, instead of trying to plan everything out — putting one foot in front of the other, and being on my journey, and being on my path and, you know, thinking about my end goal. And it really doesn't matter exactly when I reach that goal, as long as I just keep putting one foot in front of the other."

Photo Credit: Getty / Rich Fury