Foster,25, made just his second appearance between the sticks for United in the 1-1 draw against Celtic having been sidelined with injury for the past 18 months after spending two season's on loan at Watford.
"The last 18 months have been a massive frustration," he told the Sun newspaper.
"I was the number one choice at Watford so it was brilliant for my development.
"You've only got one chance at being at United and there have been plenty of players in the past who, maybe, jumped ship too early.
"I'm going to give it my all and try and force my way in."