The 26-year-old was part of the Three Lions squad in Brazil last month, working alongside Joe Hart and Ben Foster with goalkeeping coach Dave Watson.
And with Celtic’s pre-season already underway and a Champions League game with KR Reykjavík next week to prepare for, Forster admits he is glad to be hard at work again after a short summer break.
Forster takes a selfie with a young Brazilian fan during England's World Cup trip
"I've only had five days off," revealed Forster. "The season finished and straight away it was all about the World Cup.
"The World Cup finished and I was thinking about getting back here for pre-season and hitting the ground running.
"It's important we are switched on and everyone gives 100 per cent through pre-season, because we all know how big the Champions League games are."
The former Newcastle United and Norwich City stopper has been a real success north of the border, helping the Bhoys to consecutive titles and also catching the eye with his performances in the Champions League.
That form has seen him become a regular in the England squad over the last two seasons and he still believes he’s learning more with every international trip he goes on.
"You spend a lot of time around people that you're not normally around," he told Celtic TV.
"You watch and learn what other people do and try to take one or two per cent from other people and incorporate that into your game, or your training or gym work. There is plenty you can learn.
"It [the World Cup] was a fantastic experience, it was great to be part of a World Cup in Brazil.
"It would have been nice to have stayed in the competition a bit longer but we played well in the games and didn't get the results we needed.
"But on a personal level it was good to be involved. I think I learnt a lot."
