Actress-singer Jennifer Lopez says motherhood has been her "greatest joy" as well as "biggest challenge".

The superstar opened up about parenting through an Instagram post, with many pictures of herself with her twins, Max and Emme, 12, reports dailymail.co.uk.

"Being a mom is my greatest joy and happiness," said the 50-year-old star.

"My biggest challenge and my greatest triumph," she added, going on to wish "Happy Mothers Day to all!".

In one image, Max is seen sleeping on his mother's lap while she held Emme's hand. Another one showed the diva's son at her side in the studio while the others are happy selfies of the family.

Lopez also shared a special message for her own mom Lupe.

"Happy Mothers Day to my mama and to all the moms out there!. Mom, thank you so much for being so patient with me, for making me always believe that I could do anything that I wanted to do. That seed you planted made me who I am today. That was all you," she wrote.

The tribute included a video showing the actress' mother accompanying her throughout her career.

"My mom made us feel like we could do anything," Lopez said in the video.