Fitzpatrick started the first nine games, with a 4-5 record, before being benched during the bye week in favor of Mallett, who went 1-1 as the starter.
"There's a lot of times you don't have that opportunity," Fitzpatrick said. "Something was taken away from me, and I didn't know if I'd get a chance to go out there and play again. So [there's a] renewed sense of excitement and energy."
Fitzpatrick made it clear after he was benched that it wasn't easy. But he handled it professionally, as he promised he would. He and his teammates are expecting to pick back up on a lot of what they worked on during his first span as a starter.
Said Fitzpatrick: "All the experiences that have happened through my first eight or nine games, the timing with Andre [Johnson], DeAndre [Hopkins], the tight ends, DJ [Dennis Johnson], those guys, that stuff still carries over."
He admitted there might have been some positives to seeing things from a different perspective. He got a more complete view of the offense during the game and saw how plays are called.
"The last few weeks have been interesting, taking a step back and kind of watch the offense go," Fitzpatrick said. "For me to go back out there, it's kind of like a second chance for me, I guess. There's a lot of times when you don't have that opportunity, maybe. ... I didn't know if I'd have a chance to go out there and play again. Renewed sense of excitement, energy, whatever it is."
Fitzpatrick is a 10-year NFL veteran who has thrown for 1,960 yards with 11 touchdowns and eight interceptions this season.
Coach Bill O'Brien said the Texans aren't sure who will be their backup between Lewis and Savage.
But he did think Fitzpatrick might have benefited from his two-game hiatus.
"[Watching] a guy that's played in the system and a guy that knows the system in Mallett and sees how it operates with Mallett, that probably did help Fitz," O'Brien said. "You could see signs of that [Wednesday] in practice."
ESPN.com's Tania Ganguli and The Associated Press contributed to this report.