Are you fit to enjoy an extra 20 years? The authors of a new book tell Shane Hegarty how men of a certain age can stop the rot

'We've gone into a couple of pubs, as you do when you're in Ireland," says Chris Crowley. "There are a lot of big round lads in those pubs."

There certainly are, just as there are more than a few big round lads - or lads heading in that direction - in the US. Crowley and his co-author, friend and mountain-biking buddy Dr Henry Lodge (known as Harry) have a particular interest in how men tend to get bigger as they get older, and ease into retirement far too comfortably. They're in Dublin to talk about their book, Younger Next Year: A Guide To Living Like You're 50 Until You're 80 and Beyond. The title is self-explanatory, and much of the advice is admirably straightforward, pointing out how most of what we consider ageing is often self-inflicted decay. They provide no gimmicks, just what Lodge calls "the science of common sense".

"People embrace a little bit of apathy of old age because they don't see an alternative," says Lodge over a coffee. "This isn't about longevity. The point is we're all going to live a lot longer anyhow, but we really do live as if we're going to die in our early 70s. And then you wake up and, surprise, surprise you're left with another 20 years. And you can be either crawling along the floor of the nursing home or on long cross-country walks. There are people remarkably fit well into their 80s. A lot of it's luck, but a lot less than you think."

"There's a tipping point on the question of ageing. It's goofy to age the way we all do," adds Crowley.

In the book, the 47-year-old Lodge details the medical side of ageing, while the 71-year-old Crowley writes about the reality. They are a convincing double act; a doctor who helped his patient go from acting his age to being "a reasonably healthy 50". Now they ski and mountain bike together, even though Crowley admits - boasts, really - that he over-indulges and that he had the "willpower of a mayfly". "I drink almost every day and I am hard-wired for pleasure," he writes. As he has aged, though, he has become "functionally younger".

Their advice is aimed at forestalling ageing, and putting off all the bad aspects. The book does not promise that it's easy, and their publisher was a little concerned about advice recommending that people exercise six days a week, including a couple of days of weights.

"Everyone thinks of age in the terms of 'getting old and dying'. Harry says you'll get old alright, but you're not going to die, and the only question is whether it's going to be any fun or not. And the answer is it's not going to be any fun unless you do this stuff. The other thing is to realise the extent to which you control this stuff. People assume that it's their genes or whatever. It's not. Twenty per cent of quality of life is down to genes after 50. Once you realise you control it, then you think, heck, maybe I can do it."

Crowley believes that being fit as you age impacts on everyday life. "It's not about being an athlete into your 70s and 80s, that's not the goal. The quality of life that goes with this, the attitude and optimism is so utterly different from some little old guy who's walking around hurting. It translates into normal life, energy and optimism. It's not about creating a generation of athletes, but a generation who feel good when they get up and do stuff."

Men seldom buy health books, and seldom want to be told what to do, so need a bit of convincing. "Our lives are under our control until the day after we die," says Lodge. "But there's a resistance, a grumpiness when you tell people that. They say, well I had just settled in for my long winter's nap of apathy and decrepitude and damn it, you're making me get up.

"You can't tell a man to do anything. And men want to cast it as 'you're telling me what to do, so therefore I'm switching off instantly'. So in the book we never tell you want to do, but what you are doing - so saying, far be it for us to tell you what to do, but do you realise that by sitting down you are rotting? You can make a choice to rot or not rot. The moment you think it's your idea it achieves enormous power. So we were very careful to make it a 'why to' book, not a 'how to' book."

Younger Next Year has sold 300,000 copies in the US, but there are some who just don't want to hear the message within it. "I've had the worst luck with guys 100lbs overweight, they just don't want to hear about it," admits Crowley. "Some have gone for it, but not many. The fella who really needs it, who's going to waddle around, he's hard to convince."

Lodge interjects, "There's an addiction to apathy, that's a real addiction."

"And there's an embarrassment," adds Crowley. "I was careful to put in the bit about me waddling into the gym first day and feeling like a fool. And it's hard to get over that. I wish it was easier, because those men and women need it so desperately."

Just as important as the physical fitness, they say, is being committed to family and community. Too many men reach what they hope will be a fulfilling retirement, only to have their health deteriorate quickly.

"I was a lawyer for a thousand years, a very absorbing life with long hours," says Crowley. " And all of a sudden it's gone. You have all these feelings of self-doubt. There's a line in the book, that if you're walking New York in the middle of the day you feel like you've just walked out of a dirty movie. You feel guilty because you're not at your job. You have to get over that, and find the next thing. It's not easy.

"We're wired to be social. When you retire, you cut off that connection and, sure enough, you die. There are studies in the book about how the guy who goes to an empty house is four times as likely to die as the guy who has a social life. The great trick, especially for men, is to segue into a meaningful, connected life, with the things they care about. Harry makes a good point that when you're young there are all these big road signs, 'go to college', 'get a degree', 'get a job'. All the signs disappear when you're 60-65 and a lot of people just freefall. It's very scary."

"I think you should retire five years before you die," says Lodge. "In America, you look at people who are desperate to retire, and it is a fool's choice for a vast majority or people. Some small number have so many things to do that it's just transitioning into another stage of a life, but that's a tiny percentage. I would view retiring as a prison sentence for most people, if you look at what happens to us. And I think the older people bring enormous skills into the workforce. Studies of productivity of an older workforce show it is enormously productive."

They admit to being "messianic" about the issue, and in the US they've recently published a new edition of the book for women.

"Their attitude to ageing is so different," Crowley observes. "They've been through all these time changes all ready. They're not so scared as men because they're not so tied to their image as an executive or whatever. And also, women have a surge of optimism in their 50 and 60s that I did not know about. They're done taking care of the kids, they're a little bit independent. A lot of women feel, 'now it's time for me'."

Meanwhile, they insist there are a lot of people getting older without realising that it could be a golden age. "I now see Michelangelo's feeling was: the statue was there in the rock and all he had to do was free it," says Lodge. "And I walk around and I see the healthy person buried under 40, 50, 100lbs of junk. You realise that we all carry a fit healthy person - not just physically, but emotionally and spiritually - around with us until the day we die. It's a question of how you free them."

Younger Next Year by Dr Henry Lodge and Chris Crowley, is published by Time Warner Books, £12.99

Seven steps to a new you

Exercise six days a week for the rest of your life: "Exercise reverses the bizarre message our society sends older men and women that they should retire not just from work, but from life."

Do serious aerobic exercise four days a week for the rest of your life: "Life is an endurance event. Train for it."

Do serious strength training, with weights, two days a week for the rest of your life: "You do the aerobics because it saves your heart, but weightlifting might be even more important. It keeps your quality of life in good shape."

Spend less than you make: "You can live perfectly happily on much less if you quit chasing the iron bunny of material and status and things that you don't really want or need."

Quit eating crap! "Make obesity your taboo."

Care: "Being interested enough to get up every day and give it a shot."

Connect and commit: Re-dedicate yourself to family, friends, companions. Do communal things."