Leah Messer's daughter Ali is taking major physical strides, despite being diagnosed with a rare form of muscular dystrophy years ago.

After the seven-year-old child, whose father is the Teen Mom 2 star's ex-husband, Corey Simms, learned how to ride a bike, Messer took to Instagram to applaud her daughter's strength and determination.

"Mommy and daughter bonding time after therapy with her! #itsthelittlethings #mygirl #MDwontstopher #brave #strong #determination #iloveher #rockingourlipstick #mother #daughter #bestfriendgoals," she wrote in the caption of a photo of herself and Ali wearing matching lipstick.

Because Ali has been diagnosed with Titin muscular dystrophy, she is expected to lose muscle strength and respiratory function in the coming years.

Messer went public with Ali's diagnosis during a 2014 episode of Teen Mom 2 season five.

"Eventually, Ali could be in the chair all the time," Messer told Us Weekly magazine at time. "But I've never seen her so happy. She chases [twin] Aleeah and doesn't fall down anymore."

Years later, Messer's second twin, Aleeah, was tested by doctors who believed there was a chance that she could suffer from the disease as well.

“I just got back from Columbus, they said that [Ali] was getting stronger and she was doing fine,” Messer said. “They actually want to get Gracie tested for MD as well, so I’ll have to take her back up there and they’ll have to do blood work and then we’ll know.”

“She’s a child of Corey and I’s, and we carry the gene,” Messer explained to a friend. “She hasn’t been tested. We thought that she had been tested, but I guess that was for some other testing research. The possibility of her even having it is worrisome to me.”

Luckily, Aleeah does not suffer from the disease.

To see more of Leah Messer and her family, don't miss new episodes of Teen Mom 2 season eight, which air on MTV every Monday night at 9 p.m.