Erik Spoelstra hailed the "intimate" and "raw" relationships within the Miami Heat's roster after his team overcame the Boston Celtics to reach the NBA Finals.

The Heat had squandered a 3-0 lead in the Eastern Conference finals, but Game 7 went their way in emphatic fashion.

Jimmy Butler led Miami with 28 points as the Heat won 103-84, ending the Celtics' bid at history in the process.

Boston was aiming to become the first team to win a seven-game series after losing the opening three encounters, but it was not to be.

"It wasn't scripted," Spoelstra told reporters.

"When you have such an intimate relationship with a locker room and they have it with each other, the staff has it with them, they have it with the staff, sometimes it's just whatever's raw, whatever's real at that time.

"Professional sports is just kind of a reflection sometimes of life, that things don't always go your way.

"The inevitable setbacks happen and it's how you deal with that collectively. There's a lot of different ways that it can go. It can sap your spirit. It can take a team down for whatever reason.

"With this group, it's steeled us and made us closer and made us tougher.

"These are lessons that hopefully we can pass along to our children, that you can develop this fortitude.

"Sometimes you have to suffer for the things that you want. Game 6, the only thing that we can do is sometimes you have to laugh at the things that make you cry."

The Heat are only the second No. 8 seed in NBA history to make the Finals, after the 1999 New York Knicks.

Butler was named the Eastern Conference finals MVP, and has full confidence the Heat can go all the way against the Denver Nuggets.

"I just know why coach Pat [Riley] and coach Spoelstra wanted me to be here," Butler said. "That's to compete at a high level and to win championships.

"I know that the group that they put around me at all times is going to give me an opportunity to do so.

"I know the work that we all put into it, so I know what we're capable of. Nobody is satisfied. We haven't done anything. We don't play just to win the Eastern Conference; we play to win the whole thing."

Spoelstra reserved special praise for the Heat's talisman.

"There's no way to quantify the confidence that he can instil in everybody. Jimmy has never had to apologise," Spoelstra said of Butler.

"I don't want him to ever apologise for who he is and how he approaches competition. It's intense. It's not for everybody, and we're not for everybody.

"That's why we think it's like an incredible marriage. We never judge him on that. He doesn't judge us for how crazy we get. It's the same language. But the confidence level that he can create for everybody on the roster is incredible.

"He's gnarly, but he knows how to have a soft touch to give somebody some confidence at the right time. That's the special gift that he has."