“The Mummy” star Brendan Fraser was in his thirties when he first became an action star with his trio of adventure movies. Now, nearly 20 years after his last outing as archaeologist Rick O’Connell, the 57-year-old actor is getting back into shape for the long-awaited “Mummy 4.” Fraser joined Jimmy Fallon on “The Tonight Show” to tease “The Mummy 4,” which is set to release in theaters on Oct. 15, 2027. He’ll reunite with Rachel Weisz, who starred as Rick’s wife Evelyn in the first two “Mummy” movies before being replaced by Maria Bellow in the role in “The Mummy: Tomb of the Dragon Emperor.” John Hannah, who played Evelyn’s older brother Jonathan, is also back for the sequel. “We’re gonna get the band back together,” Fraser told Fallon. “The only way to do it.…