Kate Hudson and son Ryder Robinson arrive for the premiere of DreamWorks Animation and Twentieth Century Fox's "Kung Fu Panda 3." Credit: Albert L. Ortega/Getty Images

Welcome to the teen years! Kate Hudson shared a sweet message to her son Ryder on his 13th birthday on Instagram on Saturday, January 7.

"Thirteen years… Today I reflect on how lucky I am to have spent my entire adult years being Ryder's mother," the 37-year-old actress captioned a throwback picture of herself and her eldest son holding hands on the beach. "My dear Ryd man! Today you are 13! Hard to believe but I'm staring right at you and my goodness yes you are a teenager!"

"I couldn't be more in love with who you are as a person and who you are growing into as a young man," she continued. "Smart, funny, joyful, tolerant, perceptive, empathetic, loving, you continue to maintain the beautiful attributes of your true nature and I will always be there as your touchstone to help nurture them or rediscover them if they ever get cloudy. But watching you independently keep these characteristics close and alive has been a wondrous journey in which I look forward to witnessing every waking hour. Happy Birthday baby!!! 13 is looking pretty awesome so far!!! I love you #RyderIsThirteen #HappyBirthday #ProudMama."

Thirteen years... Today I reflect on how lucky I am to have spent my entire adult years being Ryder's mother ❤️ My dear Ryd man! Today you are 13! Hard to believe but I'm staring right at you and my goodness yes you are a teenager! I couldn't be more in love with who you are as a person and who you are growing into as a young man. Smart, funny, joyful, tolerant, perceptive, empathetic, loving, you continue to maintain the beautiful attributes of your true nature and I will always be there as your touchstone to help nurture them or rediscover them if they ever get cloudy. But watching you independently keep these characteristics close and alive has been a wondrous journey in which I look forward to witnessing every waking hour. Happy Birthday baby!!! 🎂 13 is looking pretty awesome so far!!! I love you ❤️ #RyderIsThirteen #HappyBirthday #ProudMama

A photo posted by Kate Hudson (@katehudson) on

Hudson shares Ryder with her ex-husband, Black Crowes frontman Chris Robinson, who she was married to from 2000 to 2007. She also shares 5-year-old son Bingham with ex-fiancé Matthew Bellamy.

In November, the Deepwater Horizon actress opened up to Us Weekly about spending time with her boys. "My favorite thing to do with my kids is movie night," she said. "It's nice when they're calm. We run around so much, so it's really nice to settle them down.… [Their] age difference is big, so it's nice to do something we can all do, where Bing's not going to, like, really hurt himself because he's trying to keep up with his brother."

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