Rob Lowe has reached a major milestone in his life.

The former "Grinder" star, 55, took to Instagram on Friday to share with fans that he is celebrating 29 years of sobriety.

"Today I celebrate 29 years of sobriety," Lowe captioned an old photograph of himself. "Thank you to all those who have inspired me on this wonderful, challenging and life-changing journey."

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The actor went on to share a motivational message as well.

"If you, or someone you know, are struggling with alcohol or addiction, there CAN be a future of hope, health and happiness," he wrote. "And it comes one day at a time. #recovery#ItWorks."

In a 2011 interview with Oprah Winfrey, Lowe revealed that his sex tape scandal in the 1980s — which nearly ruined his then-blossoming acting career — ended up being a positive thing for him, ultimately helping him get sober.

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“It ends up being the greatest thing that ever happened to me,” Lowe said of his sex tape at the time. “Because what it ends up doing is accelerating my alcohol [addiction] to where I finally get sober.

"I have been able to have the rest of my life that I’m so blessed with, which is now 20 years of sobriety.”

Fox News' Tyler McCarthy contributed to this report.