Aaron Paul paid tribute to his Breaking Bad co-star RJ Mitte after his death at 34.

The actor, who played Jesse Pinkman in the AMC series, took to social media to memorialize Mitte.

“RJ, You have always been an inspiration for so many. I am so sorry you were hurting my friend. I wish we knew,” Paul wrote. “You constantly had a smile on your face and you took every single challenge that was given to you with such confidence and grace.”

He continued, “I met you when you were a little boy and watched you grow into a beautiful young man. Taking on every challenge head on.”

Paul noted that the last time he saw Mitte he kept calling him Superman, adding, “You reminded me of him. You reminded me of him because you always led with kindness and strength. It was blinding. You were born into a world with challenges but you never let any of that stand in your way.”

The actor called Mitte’s death “an absolute tragic loss” and made a note to anyone in a difficult situation.

“I hope whoever is reading this note that feels lost or sad or uncertain about the future please say something. Life is so damn special,” he wrote. “It’s impossible that we exist, but yet we all are here. There is so much going on in all of our lives but far too much beauty in this world to ignore. We need to focus on that. We must suffocate the noise and focus on each other. Hold each other up. That’s what this life is all about. Connect with someone you care about and say I love you.”

Mitte’s reps confirmed the news, saying he died by suicide in Brownsville, Texas.

Paul ended his post saying, “RJ, love you my friend. I’m so sorry.”

If you or anyone you know is having thoughts of suicide, call or text 988 to reach the National Suicide Prevention Lifeline.

Read Paul’s complete message below.