Smith said he completed the program Oct. 28 at an undisclosed treatment center outside of California. The team activated him to the 53-man roster last Thursday. He has begun to practice with the team this week.
Smith said he is taking everything one day at a time, but the idea of playing Sunday at home against Carolina is "crossing his mind." There is a chance Smith, who turned 24 while in the treatment center, will be brought back slowly.
He said he had "good workouts" twice a week while he was seeking treatment. Smith, who leads the NFL with 38 sacks since entering the league in 2011 and has 4.5 sacks in three games this season, appeared happy and he said he was pleased he sought help. He went into treatment voluntarily three days after he was arrested for drunk driving for the second time since early 2012.
"Of course, I didn't want to be away from the sport I love, but it was good for me to get away and get my mind together," Smith said.
"I'm getting there," he said with a smile about his general wellness. "Every day is just a step closer to where I want to be. ... It's about bettering myself."
Smith said he was thankful for the support he's received from his family, friends, teammates, the 49ers organization and fans. He said it's important that he is settling back in with his daily routine at home and taking care of his 10-month-old son.
Several of Smith's teammates expressed how happy they were to see him. Many teammates and coaches kept in contact with Smith via text while he was in treatment.
"He looks happy and healthy," safety Donte Whitner said. "The key is to move forward and not dwell on the past and [I] think he's ready to do that."
Smith is still facing legal issues. In addition to the drunk-driving case, he is facing felony gun charges stemming from a 2012 party at his house. He said Tuesday he has spoken to the NFL office, but not commissioner Roger Goodell directly.
Goodell said in London on Oct. 26 that he will weigh the fact that Smith left the team voluntarily for five weeks to better himself when determining league discipline. If he is not suspended, Goodell could dock a pay check or two from Smith.
The 49ers opted to pay Smith while he was on the non-football injury list. Smith makes about $99,000 a week.