Alongside a carousel of photos of the couple together throughout the years, Hart used the caption of the Instagram post to leave a touching message about his wife and the time they've spent together.
"Welcome to 40 baby," he started. "I’ve celebrated 18 birthdays with you, and I can say it’s amazing growing up with you. The person you have grown into is inspiring. You have become a successful business woman, superstar, dedicated mother, Philanthropist, supportive wife, wine maker, motorcycle mama, and amazing friend to all around you."
Hart went on to continue, writing, "I’m so proud of the woman you have become, and you are more beautiful than ever. You truly are like wine. You just keep getting better, and I’m so lucky to be along on this crazy ride with you."
The heartfelt post finished on an even sweeter note, reading, "I love you baby. Looking forward many many more birthdays with you. I can’t wait to see how nuts you and I are in our 80’s 😂😂. Enjoy your day."
Pink also took to Instagram to celebrate her birthday. Paired with a pic of her jumping high into the sky, she wrote, "THANK YOU FOR MY BDAY WISHES. I’m jumping for joy to be 40. I’m so f’ing into it. I love you all!"
Hart and Pink first met in 2001 at the X Games in Pennsylvania. In 2005, Pink proposed to Hart, while he was racing, with a handmade sign that read, "Will You Marry Me?" The couple got married a year later in Costa Rica for a classic beach wedding.
The singer and the former motocross pro have two children together, Willow Sage, 8, and Jameson Moon, 4.
Pink has been very open about her relationship with Hart through all of their ups and downs after their brief split in 2008. In an extended interview with Carson Daly, Pink spoke about her marriage and motherhood.
“Carey and I have been in couples counseling almost our entire 17 years that we’ve been together,” she told Daly. “It’s the only reason we’re still together... We come from broken families and we had no model for, 'How are we supposed to keep this family together and live this crazy life?' And there’s no book that says, ‘Here’s how to do this.’ So we go to counseling and it works.”
Despite the bumpy road, the couple and parents of two celebrated their 13th wedding anniversary on Jan. 7. Hart shared a heartfelt message for Pink to commemorate that occasion as well.
"Can’t believe it’s our 13th wedding anniversary," he wrote in the caption. "Who would have thought two misfits like us could pull it off!!! I’m very grateful for you, baby. We have created an amazing life and family together. I love you. #17YearsStrong"
What a wonderful couple. Happy birthday, Pink!