KISSIMMEE, Fla. — While NBA bubble teams have access to luxury hotel accommodations, high-tech arenas and private concierge services, Brad Stevens and Erik Spoelstra have both gravitated toward one of Disney World’s least glamorous amenities: a 1.5-mile walking loop that surrounds the Coronado Springs Resort.

Nearly every afternoon, Stevens, the Boston Celtics’ coach, and Spoelstra, his Miami Heat counterpart, are among the many NBA luminaries raising their step counts on the property’s flat paved roads. The walk is pleasant, dotted by small lakes that are home to alligators and turtles, with herons and anhingas lining the banks. Geckos, frogs and the occasional armadillo roam the sidewalks, while dragonflies and butterflies buzz along between palm trees, tropical flowers and mushrooms.

Major stops include the heavily guarded front entrance to the Gran Destino Tower, the shipping facility that has received thousands of packages during the NBA’s restart, and small fields near the media housing complex that play host to individual workouts and pickup Wiffle ball games. The roads are mostly barren, because the closed complex is off-limits to tourists.

Stevens and Spoelstra both walk in counterclockwise fashion, and both politely wave to passersby coming in the opposite direction. Stevens refers to his routine as his “walk of sanity,” and he likes to multitask with phone calls; Spoelstra often dons a “Heat Culture” T-shirt while working out in the afternoons, typically the hottest and most humid part of the day. There’s a thick symbolism in these two coaches — who have built their respective teams on founding principles such as discipline and sacrifice — seeking balance by subjecting themselves to daily spins on a human hamster wheel in 95-degree heat.

All those thankless miles have paid off with this: Stevens’s Celtics and Spoelstra’s Heat will meet in the Eastern Conference finals, which open Tuesday. The matchup qualifies as a surprise: Boston narrowly upended the defending champion Toronto Raptors in seven games, while Miami dismantled the top-seeded Milwaukee Bucks in five. Neither team’s central players have NBA Finals experience, but both organizations have thrived in the bubble through balanced offense, committed defense and a steady, businesslike approach to the challenging environment.

“We’ve had to battle the emotions of a playoff series,” Stevens said, pointing to Boston’s response to a miraculous buzzer-beater by Toronto forward OG Anunoby in the second round. “Game 3 was probably as heartbreaking of a loss in a playoff series as you can have. To have to come back from that and re-center, that’s where the positive comes in. We’ve been through a range of emotions, for sure.”

The Celtics and Heat last met in the playoffs in the 2012 Eastern Conference finals, when a magnificent performance from LeBron James in Game 6 helped Miami avoid catastrophe and go on to win the first title of its “Big Three” era. There is no love lost between these two rivals, as evidenced by a famous 2013 news release issued by Heat President Pat Riley that targeted Celtics President Danny Ainge.

“Danny Ainge needs to shut the f--- up and manage his own team,” Riley said, in response to Ainge’s comments about James working the officials. “He was the biggest whiner going when he was playing and I know that because I coached against him.”

While Riley and Ainge remain in charge, the key figures from 2012 are largely gone. Nevertheless, these two teams arrive at this series with many interesting parallels. Boston and Miami rank first and second, respectively, in cumulative wins among Eastern Conference teams over the past 20 seasons. That shared sustained excellence has produced super teams and championships on both sides, with the Celtics claiming the 2008 title and the James-led Heat winning in 2012 and 2013. Boston and Miami both endured lulls after their title cores collapsed, but they quickly rebuilt thanks to savvy front offices that drafted well, aggressively pursued stars in free agency and swung favorable trades.

“I have two sons now, and it would be like trying to compare kids,” Spoelstra said, when asked how his 2020 team stacked up to the “Big Three” Heat. “I’m a steward of this culture, and I’ve been fortunate enough to be a part of the Riley [and owner Micky] Arison leadership for 25 years. We’ve built many different teams that looked a lot different, all with the same goal.”

For Boston, the major turning point came with the selection of all-star forward Jayson Tatum in the 2017 draft. That pick solidified a core wing duo with Jaylen Brown that gave Boston a versatile base with which to build effective two-way lineups and create matchup problems for opponents. Despite their youth, Tatum and Brown are in their third playoff run together and are returning to the East finals, where they lost to James’s Cleveland Cavaliers in seven games two years ago.

“It feels different, just because my first year [in 2018] I didn't know what to expect,” Tatum said. “It was just my first go at everything. Now I can say I've been here before.”

Meanwhile, Miami accelerated its timeline by gambling last summer on a sign-and-trade for Jimmy Butler. The all-star forward’s arrival gave the Heat a leading personality and a capable late-game closer, and his fearlessness has set the tone throughout their bubble run. Yet Butler wasn’t eager to cast himself as the hero, not even against a longtime nemesis in Marcus Smart, Boston’s defensive stopper.

“I’m not going to sit here and make it about me vs. him because that’s not the case,” Butler said. “I don’t think he can win it by himself with the Celtics. I can’t win it by myself with the Heat.”

Indeed, Tatum and Butler will function as this series’ headliners, but their teams are here because they receive offensive contributions from all five spots using spread lineups that feature four perimeter threats around a versatile big man. Boston center Daniel Theis has distinguished himself as one of the bubble’s most unheralded impact players with high energy play, while Miami center Bam Adebayo made his first all-star appearance this season by blossoming into a do-everything talent who can score, rebound, pass and cover ground defensively. Adebayo’s passing from the high post creates scoring opportunities for Miami’s supporting cast around the basket.

“This is probably the closest team in the East that we’ve seen to the [Golden State] Warriors with regard to their cutting and shooting,” Stevens said.

The point guard battle looms as a key fulcrum. Boston’s Kemba Walker is the X-factor for the series, in part because he faded toward the end of the second round. With Toronto frantically climbing back into the series, Walker scored just five points in a Game 6 loss and 14 points in a Game 7 win. The Celtics will need more than that against the Heat, which boasts the East’s most efficient offense in the playoffs.

“It was tough,” Walker said. “Toronto [used a box-and-one defense on] me. I was struggling to make shots the second half. My teammates encouraged me so much to keep shooting the basketball, keep making plays as much as I can. Even though I still struggled, we were able to come out and get a win. That’s because my teammates allowed me to stay levelheaded.”

Goran Dragic has been a revelation for Miami at point guard, shifting from a reserve role in the regular season to a starter throughout the playoffs. The Slovenian pick-and-roll maestro is averaging 21.1 points and 4.7 assists during the playoffs, and his shot-making flummoxed the Bucks. Boston has the stingiest playoff defense in the bubble, and containing Dragic will surely be a top priority.

If the top-line positional matchups are fought to a draw in what most observers expect to be a tightly contested series, other questions on the margins will determine who advances.

Will Gordon Hayward, who has been sidelined since the first round with an ankle injury, be able to return to add stability to Boston’s second unit? Can Robert Williams and Grant Williams, Boston’s backup big men, continue to buy enough rest time for Stevens’s starters? Will Miami second-year forward Duncan Robinson and rookie guard Tyler Herro continue to look comfortable, or will they begin to wilt under pressure? Will Jae Crowder regress after shooting a red-hot 22 for 51 (43 percent) from beyond the arc against Milwaukee?

In addition to their exercise routines, Stevens and Spoelstra share an affinity for remaining tight-lipped on strategic matters. Both coaches were less than forthcoming in their interviews Monday, although Spoelstra revealed with some satisfaction that the Heat’s travel logistics were simplifying.

Rather than being required to travel to off-site gyms, Miami’s designated practice facility for the conference finals is now — appropriately — within walking distance.

“We earned that right,” Spoelstra said, a hint of a smile visible behind his face covering. “No more buses.”

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