It helps, she notes, that many people in their senior years enjoy the enviable advantage of substantial disposable income and sufficient time in which to enjoy it.
"This makes the grey pound extremely important, and means people can live out their long-held dreams," she says. "With inheritance tax at 40 per cent, my philosophy is very much the same as Rabbi Hillel's, who said if not now, when?"
She recalls how her late husband, the BBC executive and documentary-maker Desmond Wilcox, "blew his whole pension on my 50th birthday and we went to Australia. Thank God he did that, because it gave us quality time and memories which are so much more important than money."
Wilcox died aged 69 in 2000, the victim of heart disease. Eight years on, Rantzen still feels the pain of his early death. "My main regret is that Desi should have had another 20 years. But it wasn't in my gift. The only sadness for me now is that Desi is not still here."
The pair met in 1968. Wilcox was Rantzen's department head at the BBC, and also married to her friend and colleague, Patsy Wilcox. The affair caused a scandal, with working relationships suffering at the very moment when Rantzen was achieving her greatest success as host of the consumer-rights programme, That's Life, which peaked in 1977 with ratings of over 22 million.
Patsy reluctantly agreed to grant Desmond a divorce only when Rantzen became pregnant. The couple were married in 1977, a month before their eldest daughter Emily was born.
Wilcox then converted to Judaism and in 1999 they held a second wedding at the Liberal Jewish Synagogue in London. "That was one of the highlights of my life so far. It was a lovely ceremony. I remember it with very great affection," says Rantzen.
Although she says that being Jewish is a central part of her identity, she admits that she was not observant and that Wilcox was "more religious" than she was. "He converted me to Judaism," she jokes.
But recently, Judaism has returned to her life in a meaningful way, with her daughter Emily becoming involved with the Kaballah Centre. "She has become quite observant. She observes Shabbat and eats kosher. She will only eat vegetarian at my house. She has brought Judaism back into my life in a big way. I didn't really observe the festivals too much before. My other daughter Rebecca and my son Joshua are not observant, but Rebecca is starting to think about joining a synagogue.
"I'm a member of the Liberal Jewish Synagogue. If my children wanted to go to a synagogue, I would certainly go with them."
At Pesach, Rantzen accompanied her daughter to a Kaballah Seder night in Miami. "It was fascinating watching 2,000 people observing Pesach. I can see why my daughter enjoys their company. I do get very surprised by the venom that I hear about [the] Kaballah [Centre]. I think part of it is Madonna-envy. It's also about money. People have this feeling that Kaballah Centres make a lot of money. And there is a traditional aspect too in that kaballah is meant to be a secret for married Jewish men. The idea that unmarried Jewish women could learn the secrets is seen as blasphemy. My philosophy on the matter is just live and let live."
Aside from her daughter's increasing involvement with the group, Rantzen says that her Jewish identity was also strengthened when she was the subject of the upcoming genealogy BBC series Who Do You Think You Are?. Due to air in September, it allowed Rantzen to discover much about her past, she says. "It was so interesting finding out about my roots. My sister has been delving into our past for a while and it's fascinating."
As a woman who has fronted several of the nation's most popular television programmes, as well having founded ChildLine, the free helpline for children, and working with numerous other charities including Help the Aged and Marie Curie Cancer Care, Rantzen admits that her public persona can vary widely. "I never quite know which me people want. I think people see me differently according to what's important to them."
So has she ever encountered any hostility to her seemingly never-ending charity work? "No," she insists. "I haven't come across any compassion fatigue or anything like that at all."
One of the things she is proudest of is ChildLine. "Over two million children have been helped, and we know we have saved lives," she says.
But having for many years championed better child-protection measures, she now feels that children may be the victims of a culture of over-protection. "Where has the common sense gone?" she asks. "When we started ChildLine, it was because many more children than we thought were being abused. But now our children run the risk of never knowing a real cuddle."
She feels that the Criminal Records Bureau checks are in urgent need of reforming. Under the current system, anyone working with children or vulnerable groups must undergo a check every time they take a job or volunteer. "The checks should be done once in someone's life and should work as a passport, where if you get a conviction, it gets stamped. It would work better," she suggests.
She pauses, and laughs: "That's the thing about being this age - you have the self-confidence to express your opinions."
Rantzen intends to spend at least some of this golden age in the kitchen. "I'd like to learn more about cooking. I only have about six dishes that I can make, so it would be good to have some more," she says.
And letting her Jewish-mother streak poke through, she adds: "And I wouldn't say no to grandchildren."
If Not Now, When? is published by Headline Springboard at £16.99
Snapshot
Born:
June 22, 1940
Education:
North London Collegiate School and Somerville College, Oxford
Family:
Married BBC documentary- maker Desmond Wilcox in 1977 and then again in a Jewish ceremony in 1999 after he converted. He died in 2000. They have three children, Emily, 30, Rebecca, 28 and Joshua, 26
Career highs:
Produced and hosted the BBC consumer show That's Life, which had 22 million viewers at its peak. Hosted awards shows Hearts of Gold and appeared as a contestant on Celebrity Strictly Come Dancing. Chair of children's charity ChildLine since she founded it in 1986
Career lows:
In 2003 she was widely criticised for compromising her role as a consumer-rights champion by promoting the Accident Advice Helpline, a compensation-claims company
On her Jewishness:
"I feel I am very Jewish. It is a central part of my identity"
Over a 40-year career in which she became one of the most familiar faces on British television, Rantzen was a serial adopter of causes. She has taken up the cudgels against age discrimination by writing a book, If Not Now, When? Living the Baby Boomer Adventure. In it, she concludes that the "third age" is one of the best times of her life.