John Stamos celebrated his son Billy’s birthday with an aww-inducing video. The 57-year-old Full House icon joined his wife Caitlin McHugh Stamos, 34, in marking Billy’s special day on Saturday, April 10. “I can’t put into words the magnitude of the love I feel for this little guy,” John wrote in the caption of his adorable video. “Happy Birthday Son. God only knows what I’d be without you. #aftershowerseries.” The actor shared a montage of him holding his son after showtime, showing how much the little one has grown over the years.

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Tugging at everyone’s heartstrings, John set the slideshow to “God Only Knows” by the Beach Boys. The video displays their sweet father-son bond, displaying John’s mirror selfies. John and Billy laugh together, make funny faces, put on shaving cream and more in the montage. Fans and the star’s celebrity friends alike were smitten with the clip.

The beloved Beach Boys’ tune is clearly a special one for John and Billy. The Big Shots leading man previously shared a previous VIP video of him and Billy listening to the band play the track live from side-stage of a concert.

Caitlin shared her own charming tribute, posting a carousel of Billy’s “week long” birthday celebrations. “Today marks the end of a week long celebration of Billy’s 3rd birthday!” the mom wrote.

She revealed that their son had quite the array of festivities, adding: “We started with an Easter/ghost party with family. Then, a Halloween ghost party with preschool friends, then a joint birthday celebration with my 94 year young grandpa (who we’ve finally been able to see after over a year)! It feels like yesterday he was the little nugget in the last couple of pics. Now, he’s a bright, social, wild child with a love for Halloween.”

The Stamos’ are head over heels for their son, who changed their lives for the better. “Fatherhood is the best thing to ever happen to me,” John said last Father’s Day. Happy birthday, Billy!