Fitzgerald started the second Test on the wing but was dropped from the matchday 22 following the narrow defeat in Pretoria.
And the 22-year-old Leinster utility back has admitted that the frustration of not playing a part in the Lions' final triumph has ensured he is even more determined to succeed with province and country this season.
"I made a conscious effort to really kick on and use it as a motivating factor for me," Fitzgerald told The Irish Times ahead of Ireland's clash with Australia on November 15.
"This year I've started to do that. I've only started a few games so I don't want to jinx anything but I feel very strong and very confident at the moment.
"I suppose it could have gone two ways: I could have got down on myself and started doubting myself but I decided I'd work harder on my physical development and I decided I should back myself more and trust my own instincts.
"I was obviously really disappointed to get dropped. I made one or two errors in the game which maybe cost me the position. It was pretty cut-throat stuff out there. From a personal perspective it was disappointing. It was a good finish from a squad perspective but not from a personal one."
Fitzgerald has begun to impress again in recent games and appears a near certainty to start for his country against the Wallabies in just over a week's time.
If he does get the nod from Declan Kidney for the Croke Park showdown with the Lions' next opponents, he intends to go looking for ball as often as possible, even if he is unlikely to start the game in either of his favoured positions.
"It's about putting myself in with a shout of getting into the team for the Australia game," added Fitzgerald.
"I think everyone has the same goals at this stage. And if I was involved I want to get my hands on the ball as much as possible. That's one of the things I really targeted this year with Leinster, and if I'm picked for the team next week it's something I'll be really targeting, to try and get involved in the game as much as possible.
"My favourite position is actually fullback, but for some reason, no one wants to play me there!
"I've got to bide my time because there is a lot of competition for that fullback spot. The real challenge for me playing as a winger is to get touches on the ball and get involved in the game.
"The centre I enjoy, but I'd probably consider myself an outside centre. Obviously there's a certain number 13 who is immovable."
Unsurprisingly, given the huge array of Lions talent within the current Ireland set up, Fitzgerald is confident that the 2009 Grand Slam winners can continue their unbeaten run this autumn, even if he knows history suggests otherwise.
Ireland face Fiji a week after taking on the Wallabies, with Fitzgerald and co then given a chance to avenge the Lions' demoralizing second Test defeat to the Springboks when they challenge South Africa in Dublin on November 28.
"This team will be going out to win every match it's playing.
"You've got to respect these guys. You can look at the history books but I don't think it will really benefit us because we haven't done so well against them. We'll be trying to treat every game as an entity itself and we'll try to win every game."