Kylie Jenner (Photo: Axelle/Bauer-Griffin/Getty Images)

Kylie Jenner is experiencing postpartum symptoms after welcoming her second child, a son, in February.

The cosmetics mogul shared a mirror selfie video today on her Instagram Stories during her workout. In the clip, she wears a tan sports bra paired with brown bike shorts. “NO DAYS OFF!” she wrote.

Though fans on social media pointed out how fit the star looks just a few months after giving birth, Jenner said she hasn’t regained all her strength just yet.

In a second video—this time of her walking on a treadmill—Jenner wrote, “4 months postpartum. i have been dealing w tons of back & knee pain this time so it slows down my workouts but i am on a mission to get strong again.”

The youngest Jenner previously opened up about how she was feeling after welcoming her son—whose name we don’t yet know. In March, one month after the birth of her second baby with rapper boyfriend Travis Scott, she shared a set of videos on her Instagram Story and said, “I just want to say to my postpartum moms that postpartum has not been easy. It’s not been easy, it’s very hard. This experience for me, personally, has been a little harder than with my daughter.”

Scott and Jenner are also parents to four-year-old daughter Stormi Webster.

She added that social media can be misleading to some moms. “It’s not easy mentally, physically, spiritually, it’s just crazy,” she continued. “I didn’t want to just get back to life without saying that, because I think we can look on the Internet, and for other moms going through it right now, we can go on the Internet and it might look a lot easier for other people and, like, put the pressure on us, but it hasn’t been easy for me either, it’s been hard.”

Jenner said at the time, “Once I realized that … I was putting some pressure on myself, and I just keep reminding myself I made a whole human—a beautiful, healthy boy. And we have to stop putting pressure on ourselves to be back—not even physically, just mentally—after birth.”

This article originally appeared in Harper’s BAZAAR US