Work-life balance used to be a ­minority interest - important to recent graduates and working mothers with children, but scorned by most ­employees. Until recently, the workplace was dominated by baby boomers - the generation born between the end of the Second World War and the early 1960s - and they believed that the key to success was hard work and long hours.

The word generation is a shorthand used by social scientists and pop culture experts to describe gene­rally how groups of people think and behave - it doesn't mean everyone in that demographic will always act like that, or that no one else will. But, on the whole, it works.

Although most senior management positions are still filled by career-driven baby boomers, the workplace is now filling up with gene­ration X (people born between the early 1960s and the early 1980s), and they have a different attitude to work-life balance. Generation X started working at a time when employers were announcing that the job for life was over, and so they have a very different notion of what they owe to their bosses. They also grew up in an era of relative affluence and have higher expectations in terms of quality of life. Generation X values time as much as money, and they won't give it up lightly.

Generation Y - kids born from 1980 onwards who are just entering the ­labour market - are even more ­focused on work-life balance. Where baby boomers see life as a period of study, followed by work, then leisure (retirement), generation Y is used to doing all three at once. A survey of 26,000 European university students found that work-life balance is now the most popular ­career goal (Universum Graduate Survey 2006).

As the oldest baby boomers hit ­retirement age, and generation X starts to take the reins of senior management, work-life balance is going to factor a lot more in organisations' thinking - and in the packages they offer to employees. The top team at Hudson, a leading UK recruitment business, told me that senior-level candidates almost invariably say that they want a healthy work-life balance in their next job, which would have been unimaginable a decade ago.

Baby boomers are also starting to demand flexibility, often as a side-­effect of our ageing population. With more than 400,000 people in the UK aged 90+, an awful lot of people in their 50s and 60s are caring for their own parents. By 2020, up to nine million people in the UK - out of 25 million workers - will be providing care for older or disabled people. The pressure for work-life balance is only going to get stronger.

Steve Crabb is editor of

People Management