It's McGowan's third chance at making his mark in the Majors after dealing with a string of shoulder surgeries from 2008-10. The Georgia native had a quick stint with the club in 2011, his first appearance in over three years, before undergoing another shoulder surgery in 2012.
"If it could have went wrong, it went wrong in those three years," McGowan said.
The physical tolls, including "normal" soreness, have become something he's learned to tolerate and work with. McGowan recorded 16 strikeouts over 10 relief appearances with Class A Advanced Dunedin and Triple-A Buffalo before being reinstated from his rehab assignment.
"This game, mentally, will wear on you. It's still hard to do it, but over time you just learn," McGowan said. "You go through it so much, it just becomes second nature to you."
Each time he's on big league soil, it's like getting called up for the first time. Now, it feels decidedly different than in 2011.
"Oh yeah ... it's never going to be easy," McGowan said. "I think now, as you get older, you accept it and you know you've got to work hard to get through it."
McGowan joined a Toronto bullpen that entered Saturday's contest with 17 2/3 consecutive scoreless innings, before closer Casey Janssen gave up a pair of runs in the ninth inning.
Manager John Gibbons expects to handle McGowan in the same manner as Janssen -- using him for a maximum of two innings, followed by a day of rest, if possible.
Left-hander Evan Crawford was designated for assignment to clear a spot on the 40-man roster for McGowan.
McGowan entered Saturday's game in the 10th inning and pitched one-third of an inning, walking one, striking out one and hitting a batter.