But experience has told him the butterflies are a positive.
He knows that when he has that slightly empty feeling, that tingly surge of adrenalin that comes before taking the big stage, he’s likely to get the best out of himself.
Johnson, one of the rarest talents in the competition, has travelled to the MCG for years.
It is a special place marked by special performances – most notably the display that earned him the Norm Smith Medal almost 12 months ago.
Each time the forward sets foot on the ground, he is thankful for the opportunity.
"I can remember the first time I played there," he told gfc.com.au.
"It was in about under-11s at half time … I think all the areas got a go and I think I was playing for Wangaratta Auskick.
"I think we got beaten but I'd like to think I went alright.
"It was a buzz and I always dreamed [since that day] of playing there in an AFL game."
Johnson doesn't remember too much more of that game but distinctly recalls Hawthorn champion Dermott Brereton trotting off the ground as he took his turn at half time.
And even when his opportunity was up, he didn't think it would be the last of them.
"I always thought I would [return at a higher level]," he said.
"I always used to travel down and watch a fair few games when I was barracking for Collingwood.
"The whole family had an AFL membership so we used to travel down probably six or seven times a year.
"Mum and Dad always said that my brother and sister would sit there and stuff around in front of the chairs, but I’d sit there with my eyes glued on the footy."
A future Steve Johnson or two could be watching from the stands on Friday night as the real one struts his stuff, but it doesn’t come quite as easily as the lackadaisical Cat makes it look.
"I think I’ll be a little bit nervous," Johnson said when asked of any pre-match jitters.
"I tend not to get too nervous before games. I’ll probably be a little bit anxious just because it is a big game and when I feel myself getting a little bit anxious, I know that I think it’s a good thing.
"You can’t go into a big final just thinking it’s going to happen. You’ve got to be thinking about your performance and hoping you do well.
"It’s definitely a good feeling, you’re going to go out and play in front of 80,000 people. It doesn’t happen too often so you can’t take those sort of occasions for granted."
Some teammates will sit quietly with iPods, listening to music and trying to visualise their games.
Others, like Gary Ablett, might indulge in a game of 'golf footy' to ease any pre-game tension.
"I probably am one of the players who stuffs around a little bit and keeps the mood a bit lighter amongst the group," Johnson said.
"I sort of like to just play around with the footy and I don’t really switch on about the game too much until the siren goes."
But when that first ball is bounced, Johnson will revert to that kid from the country with eyes only for the footy.
