The question of ageism in broadcasting has been in the spotlight again recently, after Miriam O'Reilly won a landmark age discrimination case against the BBC for her dismissal from Countryfile.
Speaking to the Press Association, Britton said: "Sometimes there's a natural end to anyone's career, male or female, and you have to be very gracious when you accept it's coming because we are all freelancers, we are not in a job for life.
"Sportsmen don't moan and groan that they are thrown out of their clubs when they reach 32. It's the reality."
The former This Morning presenter added: "Sometimes, when you get older, you have to think, 'It's their turn, I've had my turn.'"
Britton also ruled out cosmetic surgery, saying: "I know we should all be going on until we're 106 but I'm not going to be having any Botox or fillers or a facelift because I have the face I should have for the age I am.
"And I think one of us has got to blaze the trail and say, 'No, this is how it is,' and if I lose my job because of it, that says a lot about the person who sacks you.
"I'm very grateful to the feminists who went before, but some things you just have to accept. I'm not expecting it to last forever because I'm a realist."
Britton's new teatime chatshow Fern begins on Channel 4 at 5pm on March 28.