Callum McGregor believes mental strength is more important than physical fitness in adapting to his punishing Celtic and Scotland schedule.
Last season the midfielder played more games than any player player in Europe as he racked up 69 appearances between club and country, winning the domestic treble with Celtic in the process.
Neil Lennon's side began their season back in July for the Champions League qualifiers, but the 26-year-old doesn't fear burnout.
He told the Celtic View: "You're playing around 60 games a season with Celtic, and if you can manage that then the nine of 10 games with the international team take care of themselves.
"Once you get to the level of fitness where you play every week, then it just becomes a mental thing and tiredness doesn't come into it.
"It's more of a mental thing, and you just prepare for the next game. If you feel good in your head, then you can go and play as many games as you can."
McGregor has become a mainstay of the Celtic midfield, but his a relative newcomer compared to club captain Scott Brown .
"To play alongside Broony every week is a learning experience.
"He's been so good with everyone in the squad, and for me to go in and play beside him as one of two controlling, then breaking from there, is amazing.
"You learn every bit of the game in terms of your defensive duties and making tackles and blocks, and starting things as well.
"There's a good balance to it now in terms of us controlling games and controlling space. When one of us goes ahead with the ball, the other stays.
"We have that really good understanding now and that Rennes game probably epitomised the system we've been playing."
