Celtics president of basketball operations Brad Stevens vowed that changes were on the way after a season that began with championship expectations ended short of a return to the NBA Finals.

Boston took its first steps to ushering in its latest era with the introduction of Kristaps Porzingis today.

Porzingis said the team’s faith in him is motivating as he begins his fourth stop in the league.

“It’s the most exciting feeling that you can get,” he said. “Just the idea of that. … It made it super easy. It made (the Celtics) my complete, favorite option.”

The Celtics netted the 7-foot-3 forward from the Washington Wizards the night before the NBA draft, executing a three-team trade that also included Marcus Smart — who’d been Boston’s most-tenured veteran — heading to the Memphis Grizzlies.

The decision to part with Smart, the 2022 Defensive Player of the Year and the team’s vocal leader, was one that coach Joe Mazzulla called “tough.” He said he spoke with Smart shortly after the deal was completed.

“I was able to talk to him, and I just told him that I love him and I appreciate who he is as a person,” Mazzulla said. “You’re never going to replace a guy like him.”

But Boston is hoping the addition of Porzingis, the fourth pick of the 2015 draft coming off one of his best NBA seasons statistically, can bring a different dynamic playing alongside All-Stars Jayson Tatum and Jaylen Brown. They will now constitute the lead trio of a group that also includes veterans Derrick White, Malcolm Brogdon and Al Horford, along with fellow big man Robert Williams.

Porzingis said the success of the current group and history of the Celtics franchise is what excited him most about the trade.

“The opportunity to play for a really good team already, and to be able to add to that and hopefully to help these guys make their lives even easier … made it extremely easy for me to make that decision,” Porzingis said.

The Celtics also are likely not done, despite already having entered into luxury tax territory by signing Porzingis, who exercised his $36 million player option for next season prior to the trade.

Stevens said he’s been given the “green light” by team owners to make necessary tweaks to the roster in free agency.

The team will also need to try to figure out a possible extension for Porzingis as he enters the final year of his current deal. In addition, on July 6 Brown will also be eligible to receive a contract extension worth $295 million.

“We’re trying to win and everybody is very supportive of that from the top down,” Stevens said. “We’re going to try to put our best foot forward and do that. The required part is the right talent to build around it. We’re very fortunate to have a lot of talented players. … We’ve got guys under contract here that are really good players. Building a team that fits around that in the best way we can is what we’re trying to do.”