SANTA CLARA — The last time the 49ers lost in the Super Bowl, the world shut down. The COVID-19 pandemic halted football activities and forced teams to cram a rushed training camp right before the season began, interrupting the NFL’s circadian rhythms. The Niners went 6-10 and missed the postseason in that 2020 season.

Jimmy Garoppolo’s high ankle sprain limited him to six starts as injuries doomed San Francisco’s quest to return to the Super Bowl. This time around, after the second Super Bowl heartbreak of the Kyle Shanahan era, the 49ers have a fully healthy Brock Purdy and an upset star receiver in a contract dispute. They have a better understanding of what it takes to return to the pinnacle of football, but a certain existential dread that comes along with a second bout of near-immortality.

“It does when you lose the games,” said Nick Bosa when asked if doubt about returning to the Super Bowl sets in. “But I think that passes, then you get to work and you really have no other option but to grind it out again.” The grind has led to the opening of training camp on Tuesday, when Bosa, George Kittle, Kyle Shanahan and John Lynch addressed local media at Levi’s Stadium.

“This one went a lot faster,” Shanahan said. “I think that is the tough thing about going to the Super Bowl and stuff, whether you win or lose — how long it takes with some of the things you put off all the way to February. Recovery you need, just mentally and physically.

But when you.