The popular forecaster, 60, has been with BBC One's morning news show since 2000 and BBC News since 1998, and has said she'd love to stick around indefinitely, but doesn't expect to still be in the role at 70.
Speaking to the Western Mail, Kirkwood said: "I try not to worry about things I can’t change. I don’t want to go, but one day it’s going to happen.
"Hopefully, it will be natural but I also have to acknowledge I’m 60 and am unlikely to be at the BBC when I’m 70, I would have thought.
"It’s the natural course of events… I don’t want to be using a stairlift to get to the studio in the morning. But I love my job."
Kirkwood has recently waved goodbye to two of her long-standing Breakfast colleagues after Louise Minchin and Dan Walker both quit their jobs hosting the programme.
Her other co-stars over the years who have now left the show include Bill Turnbull, Sian Williams, Susanna Reid, Jeremy Bowen and Natasha Kaplinsky.
The TV star, who took part in Strictly Come Dancing in 2015, recently announced her engagement on BBC Breakfast to congratulations from former co-stars and fans of the show.
Watch: Carol Kirkwood announces engagement on BBC Breakfast
As she presented a weather update from the Chelsea Flower Show, host Sally Nugent said: "I’m a little bit concerned about you this morning. I don’t know how you’re managing to stand up with that giant rock on your left hand, Carol."
Kirkwood replied: "Oh that one, thank you Sal. It is rather nice, I got engaged."
She added: "We went out for a picnic, I had absolutely no idea. The weather was glorious, we were sitting chatting, and then my other half was a wee bit nervous and he was fumbling in his pocket and then out came a ring.
"I thought he was joking actually, I didn't believe him. But it was quite romantic. You're making me really embarrassed now."