"I'm an athlete so I have to be strong," the pop star tells PEOPLE
Credit: Andrew Macpherson

After delivering daughter Willow Sage 15 months ago, Pink was in no rush to lose the 55 lbs. she gained while pregnant.

“I love to feel fit. I love to feel healthy. I wasn’t in a race,” she tells PEOPLE. “I was really kind to myself because I was actually really impressed with the fact that I had just had a baby, like ‘I made a human!’ ”

The singer-songwriter, 33, was ready to hit the gym eight weeks after Willow was born, but it wasn’t easy.

“It was slow because I literally couldn’t even do a sit-up,” says Pink, whose new album The Truth About Love is out Sept. 18. “I’d had to have an emergency C-section so I was numb. And exhausted. I was really afraid because my whole life is based on abs and core.”

She kicked herself into gear with two workouts a day – sometimes on her own, sometimes with a trainer, and sometimes along with fitness DVDs from celebrity trainers Jeanette Jenkins and Jillian Michaels.

“I’m an athlete so I have to be strong,” explains the pop star, who’s known for her extremely physical concert moves. “It was hard work, and I’m still getting there – I’m still 10 lbs. away from my pre-baby weight.”

These days, she works out for an hour and half five days a week plus rehearsals, and has been trying to stick to 1,200 to 1,400 calories a day with Freshology meal deliveries.

But, Pink says, for her the key is being realistic.

“I do the best I can,” she explains. “I don’t stick to it. I drink wine. Every day is a cheat day!”

For more on Pink s new life – including how she’s raising her daughter, her musical inspirations, plus how she navigates the ups and downs of marriage – check out this week’s issue of PEOPLE, on stands now