Demi Lovato just turned 25 and her co-artists and friends did not miss their chance to greet the celebrator on Sunday. Among those who remembered her special day was Nick Jonas, who wrote a heartfelt message to his long-time colleague. In an Instagram post, the "JONAS" alum shared his latest and old photos with Demi Lovato along with his birthday greetings.

Nick, celebrities greet Demi on her special day

Happy birthday, [Demi Lovato]. We've seen a lot of life together already.. much more to come as well," he captioned. "I admire you so much and am so grateful to have you in my life. Wish I could be with you today to celebrate! I know you won't ever let me live it down that you're a month older than me."

Nick Jonas has been friends with Demi Lovato since they shared the big screen for 2008 film "Camp Rock" where they played the roles of Nate Gray and Mitchie Torres, respectively.

In fact, Nick and his brothers, Joe and Kevin, helped the singer-actress write and record her first full-length album, "Don't Forget," which was released in the same year.

Even after the filming and promotions of "Camp Rock," the two have remained close and have been supporting each other in their respective endeavors. The "Stone Cold" artist even attended the Los Angeles premiere of "Jonas Brothers: The 3D Concert" to show her support to her co-star.

How friendship started for Nick and Demi

The two reunited to reprise their roles in "Camp Rock 2: The Final Jam" in 2010. Nick Jonas previously admitted that he became closer to Demi Lovato since she was then dating Joe. "[Demi and I] became even closer because it was never going to be romantic. [We] were productive -- we'd write songs about [their relationship]," he told Billboard.

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The singer-actress, however, briefly distanced herself from her close friend when she got involved in a controversial incident also in the same year. She went on to reveal that she had to spend some time sober after the treatment before she actually felt comfortable talking with him again.

Demi Lovato and Nick Jonas reunited on "The X Factor" stage where the latter joined as a guest mentor. The female judge described their performance an "emotional reunion" and thought that she has "got one of [her] best friends back" after getting treated for bulimia.

The "Kingdom" actor also celebrated with his friend when her single, "Cool for the Summer," placed first on several music charts. They even showcased their friendship on "Carpool Karaoke" where they gamely held a street performance with James Corden.