"I told them I didn't want them coming off the pitch haggard, drawn and disappointed," said the boss. "I didn't want them going back in and moping. I'm as disappointed as they are, but they have to realise they've been part of a great match and they mustn't let that last-minute goal spoil their season.
"Last-minute goals can be such a big disappointment that it can affect your season in a bad way. It was a sickening blow after we'd worked so hard to get back into the game.
"I don't want it affecting our season and that's why I called a meeting on the pitch straight after the final whistle and again in the dressing room later on.
"I could see they were down and I wanted to nip it in the bud straight away, so as they could walk off the pitch with their heads held high.
"We'd have taken a draw when they were still 1-0 up with 10 minutes to go and it's important you get your psychology right. We thought we'd won it when they scored with 30 seconds to go.
"You have to be very professional about how you do things and that means making sure the dressing room mindset is positive.
"That's why I kept them out there and I think it had the desired effect. Hopefully, they'll come back on Monday in a good mood and ready to work hard in training."
Johnson was keen to accentuate the positives after watching his team extend the only remaining unbeaten record in the Championship.
He said: "I've reminded the lads they are seven games unbeaten and told them it's no fluke.
"This is such a good division, we should be celebrating every point we take. I keep telling them, the league is about 46 games, not just one.
"Our season is going to be full of ups and downs and it's nice at the moment that our downs are last-minute draws.