The Hoops are chasing their third straight league title as they proudly sit 24 points clear of second-placed Aberdeen after failing to remain alive in both the Scottish League Cup and Scottish Cup competitions.
Celtic also succumbed in the Champions League at the group stage but goalkeeper Forster feels that winning another premiership is the major focus now, as it was at the beginning of the campaign.
"It's been an excellent few years. It has been a bit disappointing in the cups but I feel we have shown in the league how well we can play and how consistent we can be," he said.
"The league is the competition where you play most games and fundamentally it gets you into the Champions League. You do work hard for it.
"It's what you come back in early in pre-season for. It justifies all the work you do throughout the season, if you go on and win the league. It's always something special and it will be good if it comes along.
"We're getting closer to it and are just a few wins away. We're just taking it a game at a time.
"It's something the lads have been focused on since the start of the season. We've just been chipping away at it and we're getting near so it's important we continue to pick up results and perform in a good manner as well."
Celtic take on St Mirren at Parkhead on Saturday as they look to push further clear of their nearest rivals.
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