Johnston is determined to play a leading role for Celtic in Scotland and his country further afield, especially given the mega motivation of the World Cup being held in Canada, the USA and Mexico.
The full-back came out on top against Hoops team-mate Cameron Carter-Vickers' USA team in the CONCACAF Nations League third-place play-off this week but both are likely to be part of next year's major party as hosts.
The 26-year-old said: "Every single match now is massive when you know our country obviously is going to be participating in the World Cup.
"It seems like a long way away but realistically it is less than a year-anda-half to go, so all of these matches matter.
"We want to make sure we're heading into that on the highest of highs with all the momentum behind us as a nation. It's an important time for us."
Johnston has emerged as one of the biggest characters in Jesse Marsch's dressing room and he's taken on a similar role with his Parkhead club.
He said: "You start to just kind of go on the natural progression where you come in, you're the young guy, you're just really happy to be there, you're taking it all in and all of a sudden you get some more caps under your belt.
"Before you know it, you're looking and like, 'Oh, this is a new player, how old is he? Oh, he was born in 2007'. You're like, 'OK, wait, I'm old now'.
"And you realise people are now looking up to you. I've got 53 caps.
"I really enjoy being part of a leadership group that has a strong voice with our coaching staff and with the entire player pool of how we want to run things over there. Jesse has empowered a couple of us guys and it's something I've really enjoyed.
"I've brought that back to Celtic as well - trying to help Callum McGregor a...