Dame Barbara Windsor's husband has said he cannot leave her by herself anymore because of her Alzheimer's disease.
Scott Mitchell has also said he uses moments - such as when she forgets they are in their own front room - to spur him on during gruelling training for the London Marathon, which he is taking part in to raise money for a dementia charity.
He and a number of Dame Barbara's former EastEnders co-stars are running the event in April in a team called Barbara's Revolutionaries for the Dementia Revolution, a year-long campaign formed by dementia charities Alzheimer's Society and Alzheimer's Research UK.
Dame Barbara, 81, was diagnosed with Alzheimer's disease in 2014, although her battle with the condition was only made public last year by Mr Mitchell.
The 55-year-old said: "I can't leave Barbara by herself anymore, life has changed drastically for her and of course that reflects on our whole life together.
"Don't get me wrong, Barbara and I don't just sit there in some state of continual misery, we have chats, we laugh, we watch the telly and we make each other giggle. There's still life going on, but of course that's interspersed with some of the difficult moments too."
He said that, when he gets tired and wants to stop when training for the 26.2-mile race, he pushes himself and thinks of a number of personal circumstances.
"I think of every time I have to explain to Barbara where she is when we're sitting in our front room and she's asking me if we've stayed here before - that gets me through the pain barrier," he said.
"We chose to go public with this, there are people that most likely don't understand the full effects of what happens.
"For instance, explaining to someone they are in their own home. These are just little elements of a whole mass of things."
Mr Mitchell, who married the actress in 2000, said he has to remind her regularly that he is doing the London Marathon, adding: "But she kind of clicks straight away when I do remind her, and when I tell her the team from EastEnders are doing it, she's just thrilled."
EastEnders stars including Jake Wood, Adam Woodyatt and Natalie Cassidy are among those taking part in the London Marathon to raise money for the Dementia Revolution.
They are hoping to raise £100,000 to help fund ground-breaking research into dementia, as well as boosting awareness of the condition.
Mr Mitchell has called on members of the public with ballot places in the race to join them, and for others to sponsor them.
He has also told Good Morning Britain that his wife often forgets him.
He told the ITV programme: "I have a board where there's pictures of us from the beginning. She will suddenly say to me 'How long have we been together?'. I say '25 years'.
"It's now quite instant, the forgetfulness is quite instant."
On what he fears the most, Mr Mitchell said: "I think it's when every memory will go. When, on a constant basis, maybe one day Barbara won't know who I am.
"I've had it twice. I was helping her out of the bath and she suddenly looked at me very scared and said 'Sorry, who are you?'.
"There are no words that can describe it."