Either way, it's super important to show the person you love turning 40 — whether that be your mom, dad ... birthday card and really want to pen a heartfelt message, we've compiled the best 40th ...

‘HAPPY B-DAY DAD!’ the card read on the front. The actor also posted a second photo of the inside of the card, which included a sweet message that read, "HAPPY 40TH BIRTHDAY DAD. I love you ...

Carrie Underwood’s 40th birthday was a memorable one ... Among them included the heartwarming cards that her sons, Isaiah, 8, and Jake 4, gave her. “Things Jake loves about me,” she wrote ...