The future may be unwritten, but this friendship is crystal clear.  

More than 15 years after Laguna Beach wrapped and 12 years after The Hills concluded, co-stars Jason Wahler and Kristin Cavallari have said goodbye to high school drama and hello to a new reality: Life as parents living in Nashville.

"Kristen is somebody we've gotten very close to since we moved to Tennessee," Jason—who shares Delilah, 5, and 22-month-old Wyatt with wife Ashley Wahler, exclusively shared with E! News. "We drifted apart, we were doing our own things. I got lost in my own world and she was busy having a family and kids, but she is somebody that is a dear friend who has been very supportive in this process."

Instead of meeting a teenager involved with love triangles and bad decisions, Kristin now sees an older and wiser man in Jason, who has been candid about his battle with addiction. 

"Since we've reconnected, she's seen a completely different version," he continued. "It was the product of doing the work."

That work includes speaking out about his past struggles and joining Nashville residents—including Kristin, Jana Kramer and Bobby Bones—on a special project aimed at raising awareness on substance abuse and mental health.

"Kristen can really attest to supporting the work that we're doing just because the change has happened in my own life," he said. "I'm grateful for her support, and it's been really phenomenal to reconnect with her." 

Now, Jason is teaming up with Dr. Daniel Amen's Change Your Brain Foundation to focus on the importance of brain health and how psychiatry is practiced.

"At the end of the day, mental health and addiction is not going anywhere," he said. "It's here to stay and we need to get more creative and we need to have better alternatives to the way that we treat it."

He's proof of just that.

As part of his healing journey, Jason focuses on getting plenty of sleep and exercise. He also puts a priority on his mental health by doing a morning mediation and prayer.

"Every morning, Delilah and I wake up and we do a gratitude list of not only three things we're grateful for, but why," he said. "Some mornings I've been rushed and stressed. She'll sit down and say, ‘Daddy, we didn't do a gratitude list.'"

It's just one of the many parenting moments Jason cherishes as he stays away from TV cameras and, instead, takes in the beauty around him.

"I'm at peace today," Jason said. "My life is simple today too. God, my recovery and my family are my top three priorities and those are the things that I keep in order."