Ben Affleck Returns to Family Home After Rehab Stint: 'He's Happy to Be Back with His Kids'

"He is thrilled to be back with this kids," a friend of the actor tells PEOPLE

Ben Affleck was back on dad duty Wednesday morning, after revealing that he had completed treatment for alcohol addiction in a Facebook post a day earlier.

The actor was spotted taking his son Samuel, 5, to school with his ex Jennifer Garner on Wednesday in Los Angeles. Affleck flashed a smile while carrying his son on his shoulders on the way to the car.

“He is thrilled to be back with his kids,” a friend of the actor tells PEOPLE. “Clearly you see that his kids mean the world to him.”

“He has a great support system around him,” adds the friend. “Really nice to see his friends and family gather for him — the industry too. This was his decision to be proactive to live a healthy life. He’s been very moved by the outpouring of support.”

Now that he has returned from treatment, Affleck’s friend says, “It is business as usual in the house. He picked the kids up from school yesterday, dropped them off today. As always the kids come first. They are fiercely protective of them.”

A separate source also tells PEOPLE that “Ben and Jen took the kids to school together” this morning, and adds that Affleck is continuing to live at the family home, where he’s lived through most of their separation.

“With Ben back in L.A., things are back to normal,” notes the source. “They are focusing on the kids. Ben missed them and he’s happy to be back with his kids.”

From Coinage: See Where 6 Stars Were Before They Were Famous

In the statement he gave about completing rehab on Tuesday, Affleck said his children were motivation to get healthy. “I want to live life to the fullest and be the best father I can be. I want my kids to know there is no shame in getting help when you need it,” he wrote, adding, “I’m lucky to have the love of my family and friends, including my co-parent, Jen, who has supported me and cared for our kids as I’ve done the work I set out to do.”

The Live By Night actor-director previously told PEOPLE that his favorite part of the day is taking his kids –Violet, 11, Seraphina, 7, and Sam, 5 — to school in the morning.

“I like dropping them off and having that be part of the routine and having them be used to that and know that their dad is there and takes them to school and that feels good,” Affleck said.

When asked about his greatest accomplishments earlier this year, Affleck didn’t hesitate in saying his children. “In my career or otherwise, it is the birth of my children,” he said at a Times Talk in January. “The entrance of my children into the world.”