WALTHAM, Mass. – The Boston Celtics achieved their main goal of the season, reaching the playoffs with a relatively healthy team.

And that includes Kevin Garnett.

The team’s emotional leader missed last year’s postseason with a knee injury that required offseason surgery. But this season he played 40 of the last 42 games, and the two he skipped weren’t for health reasons.

Tonight, Garnett will be in his first playoff game since the Celtics won Game 6 of the 2008 NBA finals against the Los Angeles Lakers to capture their 17th title. It was Garnett’s first, and he screamed and wept on the court after the game.

Now Boston is seeded just fourth in the Eastern Conference and faces a hot Miami Heat team in the first round.

“I’m very much looking forward to it,” Garnett said Friday. “Obviously we all know the past history with me and my injury. So this year, to be in the postseason is great for me.”

He did miss 10 games with a hyper-extended right knee and one with a sore right thigh. For much of the season, his ability to push off his legs and jump seemed compromised. Coach Doc Rivers limited Garnett’s playing time, and he finished with averages of 29.9 minutes and 14.3 points, both the second-lowest of his career.

Now he said he’s ready to do whatever Rivers asks.

“Postseason play is all about giving everything you have. I’m no exception,” Garnett said. “This is what you play for.”

Point guard Rajon Rondo missed most of practice with flulike symptoms but will play tonight, Rivers said. “I don’t anticipate him feeling great.”

The Celtics enter the playoffs after an inconsistent regular season. They were 27-27 since Christmas, the only one of the 16 playoff teams that was not at least seven games over .500 in that span. They also dropped seven of their last 10.

But they’re a veteran team with the same starting five for the third straight year. That experience should help.

“Our goal all year long was to get to the playoffs healthy,” Paul Pierce said. “I think we’ve been able to accomplish that.”

The Heat rolled down the stretch, going 12-1 since March 20 and 18-4 since March 1.

“I’ve never been a big believer in (momentum), but I think it can’t hurt,” Rivers said. “This is the best time of year. Your past sins are washed away but your past habits aren’t forgotten.”

They Celtics better not forget what Dwyane Wade of the Heat did to them, averaging 33.7 points, 8.7 assists, 5 assists and 2 steals in three games against the Celtics this season. But Boston won all three.

“I look at us as underdogs because Boston is a team that last year, if Kevin was healthy, should have been back in the finals, everyone says,” Wade said. “This year, they have what they wanted, their whole team. They’re not possibly excited about us at all. A lot of people said we weren’t going to make the playoffs.”

But the Heat ended up seeded fifth at 47-35, just three fewer wins than the Celts.

Miami hasn’t won a playoff series since the 2006 finals. Wade was named MVP of that series.

“He’s a great offensive player,” Rivers said, “but I think what he’s really improved on is he’s great at getting everybody else involved. He’s a great ballhandling guard, strong, and he can pass.”

Garnett called Michael Beasley a tough matchup with his ability to shoot with both hands. And Jermaine O’Neal doesn’t expect a late-season ankle injury to hamper him. Both are keys to a Miami defense that allowed 94.2 points per game, second-fewest in the NBA.

O’Neal feels the Heat are much changed since their last game against the Celtics, a 107-102 loss on Feb. 3.

“Absolutely,” he said. “Defensively we’re a lot better. We really depend on each other defensively as a team now.”