Elton John celebrates 35th 'sobriety birthday'

Elton John's birthday is in March, but on Tuesday he marked a milestone birthday of another sort.

"Grateful for all the love on my sobriety birthday," the Rocket Man wrote on Instagram, alongside a photo of cards, drawings and flowers. July 29 marked his 35th year of sobriety. One card in the photo reads, "Happy 35th Birthday! We are so proud of you!" It's signed by Elton's husband, David Furnish, and their sons.

Another card says, "Congratulations on 35 years! We are immensely proud of you and wish you a lovely birthday today." It's signed "Your Rocket Family." Rocket Entertainment is the name of Elton's company.

Elton has been open about his substance abuse and other addictions in multiple interviews, as well as in his autobiography, Me. He sought help, joining Alcoholics Anonymous and going to rehab, finally getting clean in 1990. In his book, he estimated he'd attended some 1,400 support group meetings. He's gone on to help other celebrities get sober, including Eminem and Donatella Versace.