"We would occasionally win against teams we had no right to beat," the two-time defending AFL premiership coach said ahead of their Hobart clash on Sunday.
The Tigers (2-10) sit second last, while the Lions (7-6), after three straight losses, rediscovered some confidence in last Saturday's defeat of Gold Coast.
They are aiming for a third straight flag and fourth consecutive grand final appearance, but Fagan has vivid memories of his early years at the Gabba.
In 2017 - Fagan's first season in charge - the Lions collected the wooden spoon but then upset Hawthorn, who finished fourth, twice in a five-win 2018 campaign.
The second of those wins came in Launceston.
"Footy's a mindset game and we've talked about that," Fagan said.
"Their good is really good ... young and enthusiastic teams find a way to win."
Brisbane have been bolstered by the return of forward Eric Hipwood, who returns for his first AFL match since partially tearing his ACL late last year.
Sunday's match will also mark Hipwood's 200-game milestone.
Darragh Joyce was omitted to make room for Hipwood in the only change to Brisbane's line-up.
Richmond have handed a debut to mid-season draftee Kye Annand, while Maurice Rioli and Tom Brown are back after recovering from injury.
Jack Ross (concussion) and Luke Trainor (hip soreness) were ruled out through injury, while Noah Roberts-Thomson was omitted.
Fagan said the Lions' forward line remained a work in progress, but that there was nothing stopping them playing all of Logan Morris, Ty Gallop and Hipwood in the front half.
They also have former West Coast captain and key forward Oscar Allen on the sidelines, recovering from a foot injury.
Gallop, who relished his role up front on last year's march to the premiership, has been impressive in stints in defence this season.
Fagan said Hipwood was viewed in a similar light.
"They're things we have to work out," he said of Gallop's long-term role.
"You can play with three tall forwards ... we've done that plenty of times before.
"But Ty's football education now ... it opens up options for us and him."
Lions co-captain Harris Andrews, who has led the team since 2023, will play his 250th game.
"As a coach, it's been so good," Fagan said of coaching Andrews.
"So reliable. He cares so much about this club and football in Queensland, full stop.
"I can't thank him enough for everything that he's done, put it that way."
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