The Buddies reached the last-four of the Betfred Cup only to lose 1-0 to Livingston at the national stadium in January.
The Paisley men then missed out on a top-six spot in the Premiership by just two goals after conceding a late goal away to Hamilton to draw 1-1 in their last pre-split fixture.
Ahead of the battle of the Saints, the St Mirren boss stressed to his players the need to make the final.
Goodwin said: "I suppose it has been a relatively successful season up to now.
"The fact that we missed out on a top six by two goals is still heart-breaking, it still really, really annoys me because it was in our own hands and we should have got the job done and we didn't.
"I don't want us to be that nearly team.
"We nearly beat Livingston in the semi-final of the League Cup, we nearly got top six.
"I don't want this to be another of those nearly moments.
"I want us to make sure that we go and do whatever it takes on Sunday to get the job done. Sunday is just about finding a way to win the game.
"If we can do it playing open and fantastic football then great but if we need to grind out a 1-0 win in the 92nd minute, then I will take that.
"We just need to find a way to get through, it is as simple as that.
"We can remember how hurt and disappointed we felt after that Livingston game.
"There is none of us within that group who want to feel that again on Sunday evening.
"Hopefully we will give a better account of ourselves and do what's needed to make sure we are in the final and have a great day out to look forward to."
St Mirren lost 1-0 in both Premiership fixtures at McDiarmid Park, with a 3-2 home win over St Johnstone in Paisley.
Goodwin knows only their best form will see the Buddies into the final.
He said: "We are confident going into the game. We have to be.
"The message to the players is always believe we can win the game, regardless of the opposition.
"I have said how good St Johnstone are at getting the balls forward early and getting it wide for crosses into the box.
"We have done a lot of work this week to try to see how we can nullify the threat they carry in wide areas.
"It is a big day for both teams, no doubt about it.
"The players will need to raise their game, we are going to have to be at our level best in order to progress."