The guard said Sunday he came to Boston from Houston after a sign-and-trade deal because of "the core group of guys they had here."
"The expectations every year for this team is to win big and that's one thing I want to do is win big," he said. "Speaking with [Rajon] Rondo during the whole free agency period, he had the same goals that I had in mind - we want to win big, get to the championship and win. And not only for one year but continue to do it.
"We're about the same age -- me, him, Jeff [Green] and a couple other guys on the team. ... So we've got the core group here of veterans and we've still got the young guys that can keep pushing for years to come."
Lee said his friendship with Rondo played a large role in the move to Boston. Rondo went to Kentucky, Lee to Western Kentucky.
"There were other teams out there. There were teams that offered me more money, but my goal is to win and there's nothing better than winning," he said. "I got a little taste of that my rookie year [with Orlando], with going to the Finals, and that route was unbelievable. My other years can't compare to that, but now that I'm here we're trying to get on that same race and that same track and win."
The Celtics needed to free up more money to sign Lee and wound up making a three-team deal with Portland in the mix. Lee is set to step into the starting lineup, with Jason Terry, also signed as a free agent, coming off the bench. The Celtics will be without the recovering Avery Bradley (shoulder) for the first two months of the season.
Lee is with his fourth NBA team in five years. He brings quickness and shooting to the Boston offense. Where Ray Allen was a catch-and-shoot player, both Lee and Terry can shoot and take defenders off the dribble.
Asked what Lee brings to the floor, Rondo said "athleticism."
"What I'm expecting to see is just an all-around player," coach Doc Rivers said. "I think he does a lot of things well and that helps our team. He can play multiple positions -- terrific shooter, terrific defender, terrific team player."