BOSTON (AP) -- There was a moment during the past month in which Marcus Smart wasn't sure where he'd be playing basketball this upcoming season.
A day after signing a four-year deal to remain in the only NBA jersey he's ever played in, Smart said he's focused on doing what he can to help the Celtics win their 18th championship.
''I'm ecstatic. This is a blessing,'' Smart said Friday.
After being in limbo since the start of free agency, Smart cemented his pact with the Celtics on Thursday. A person with knowledge of the agreement told The Associated Press that Smart will be paid $52 million over the next four years. The person spoke to the AP on condition of anonymity because the team did not disclose the terms of the contract.
Boston brings back a 6-foot-4 defensive cornerstone who has developed a reputation for toughness and doing the little things that help the Celtics win. Smart is also the longest-tenured player on the roster.
The confidence that general manager Danny Ainge is showing in his abilities is not lost on Smart, who acknowledged he knew he was entering a tough free agent market this summer.
''To be honest, I didn't know where I was gonna end up. I was just enjoying this whole process,'' he said. ''It is a business, so things aren't perfect. That's why it's called negotiations. You guys come together and you finally agree on something. We both agreed. Boston loves me and I love Boston. Boston wants me here and I want to be here. I am here. So we made it work.''
Barring any late changes, Smart's return also means Boston will be bringing back the core of the team that won 55 games and reached the Eastern Conference finals while battling numerous injuries and being without both Kyrie Irving and Gordon Hayward the entire postseason.
Smart was a huge part of the run, stepping in to a starter's role after returning from thumb surgery late in the first round of the playoffs. He averaged 9.8 points, 5.3 assists and 3.7 rebounds per game as Boston pushed LeBron James' Cleveland Cavaliers to seven games in the conference finals.
Now, James is in the West with the Lakers, and given the emergence of youngsters Jaylen Brown and Jayson Tatum, Smart said he doesn't see any reason why the Celtics shouldn't be a favorite to come out of the East.
''We demonstrated the talent and ability we had to do that last year with a few missing pieces. With those missing pieces back in action, I think it really makes it hard for teams,'' Smart said. ''I think we have a real shot.''
The signing also will allow Smart to shift his attention back to his mother, 63-year-old Camellia Smart, who continues to undergo treatment for the bone marrow cancer she was diagnosed with in April.
''When you kind of go through adversity and something like this hits you and your family, it kind of puts everything in perspective and everything else kind of becomes a blur to you and really not that important,'' he said.
He has been with her in Texas since the season ended and said she's stable and doing well.
''She's hanging in there,'' Smart said. ''This is a hard time. But at the same time, it's an exciting time for my family. So, with the signing, it kind of brings a little joy to a situation and lightens up the situation that was a little darkened for me. ... As of right now, she's doing great.''
As far as basketball is concerned, he'll continue trying to improve.
''I'm just gonna be working on all aspects of my game. The uniqueness about me is I don't do one thing perfectly or great. I do a little bit of everything. That's what makes me so unique. I'm just trying to master a little bit of everything. ... If I could just get better a little bit each year, then I did my job.''