Noam Galai/Getty Kimberly Williams-Paisley and Brad Paisley
In the photo, Brad is riding on the back of a horse kiddie ride in what appears to be the middle of a grocery store, while Kimberly has her hand over her face in embarrassment.
"It's hard to believe he's even a grown up, but please help me wish @bradpaisley a very HAPPY BIRTHDAY!! Love you!!" Kimberly, 50, wrote on Instagram.
Shortly after, stars went on to comment on her post and wished the country singer a happy birthday as well — such as Lindsay Elle, Susan Yeagley and Poppy Montgomery.
Earlier this year, Brad and Kimberly opened The Store, a free referral-based grocery store in Nashville to help people lift themselves out of food insecurity.
"This has been our dream," Kimberly told PEOPLE at the time. "People will be able to come and shop with dignity and make choices for their family."
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Through the endeavor, the couple has managed to deliver enough free food to make nearly 1.3 million meals after one year of operation.
"Delivering these meals, it really is emotional," Kimberly said. "When you pull up and they're waiting, they're waiting in the door. And I think, 'What would they be doing if we weren't showing up today?'"
Back in April, the couple discussed the key to their 18-year marriage with PEOPLE.
"Our greatest hits," Kimberly told PEOPLE. "We record the meaningful moments, the best laughs. That's a big part of our relationship—focusing on the laughter and keeping a sense of play."
Charley Gallay/Getty Kimberly Williams-Paisley and Brad Paisley
"A lot of married couples would rather do anything but spend the evening together," added Brad at the time. "That's not the case in our house."
When asked what they love about each other, Brad said: "You keep our house afloat — seeing you give birth to two kids and raise a third is amazing," Brad said to his wife, jokingly counting himself alongside sons Huck, 14, and Jasper, 12. "And you try to do the right thing all the time."
For Kim, it was Brad's "gigantic heart:" "You care about all creatures, great and small."