Vin Diesel pays tribute to“ Fast and Furious” costar Paul Walker on late actor's 50th birthday

Family, forever.

Vin Diesel is paying tribute to his late Fast and Furious costar and friend Paul Walker on what would've been his 50th birthday.

On Thursday, Diesel reflected on the upcoming 10-year anniversary of Walker's death — and remembered the joy they shared celebrating his 40th birthday — in a heartfelt social media post.

"A decade… ten long years… and yet it feels like yesterday when we were singing happy birthday to you for the big 40!" Diesel wrote. "The world isn't the same brother… as a species, one might say we are struggling. But I think of you, and I smile and know everything is going to be alright."

Alongside his caption, Diesel shared a snapshot of the pair together that featured a smiling Walker with his arm thrown over Diesel's shoulders as Diesel holds what appears to be a cocktail shaker.

"I was going through images to celebrate this sacred day. Memories flashing before me, one better than the next… but I couldn't get past this one," he explained, noting that his son, Vincent, spotted the image and called it a "timeless photo… one that will live on for generations of humanity."

The image, however, held a different meaning for Diesel. "For me, this picture represents the moment I knew we would be brothers for eternity," he wrote. "January 2010, the night before you and I went to Haiti… the passion and joy you had to simply help people. You said first responders shouldn't have to wait for anyone… and that you wanted to dedicate your life to that. First responders… that was your true self, and you were sharing it with me, your brother. Haha. To this day, I imagine if you looked up 'first responder' in the dictionary, there would be a picture of you."

Diesel and Walker visited Haiti after the country's devastating 2010 earthquake in order to help with recovery efforts. The disaster also inspired Walker to found Reach Out Worldwide, a charity that helps send first responders to disaster sites so that they can provide aid.

Dave J Hogan/Getty Images Paul Walker and Vin Diesel

"So as much as I would like to think we would be cutting cake and singing happy birthday for the big 50... We probably wouldn't… cause you would be in Maui or Morocco, or anywhere in this planet where people were in need," Diesel acknowledged, referencing the recent Maui fires and the earthquake in Morocco.

"I miss you… I love you, and I will continue to honor the beautiful soul you are," he concluded. "Happy Birthday."

Walker died in a car accident at age 40 in November 2013. His daughter, Meadow Walker Thornton-Allan, made an appearance in the latest Fast and Furious installment earlier this year. "I am so blessed to be able to honor my father's legacy and share this with him forever," she wrote of the cameo on Instagram.

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