The Hoops needed 78 minutes to finally break lowly St Mirren at Celtic Park but finally completed the task that was set out for them with a narrow 1-0 win which kept them at the summit of the Scottish Premier League table.
Forster, on loan from Newcastle United, knows that the victory was one that Celtic had to work hard for and expects more of the same as the title race with Rangers, currently two points in arrears, heats up.
"There was a bit of relief at the end but there are going to be games like that between now and the end of the season," he told the club's official website.
"It's just about getting the three points and it doesn't matter how you do it. It wasn't our best performance but we got the three points in the end.
"There will be games where we just have to grind out results and they won't be pretty. It's all about getting the points on board, it doesn't matter how you do it at this stage of the season."