Mid-career malaise is affecting most 30-45 year olds, says the Vodafone UK Working Nation report.
Based on research among 3,800 adults of various ages, the report says those aged between 31 and 35 were the most jaded.
When asked about "negative feelings" regarding work, the 31-35 year old age bracket topped the poll in every category, including "feeling undervalued" (59%), being "unfulfilled" (49%) and being "de-motivated" (43%).
The survey also found that 97% of those working beyond 65 feel "enabled" in their work, compared with just 61% of 31-35 year olds.
Seven out of 10 workers aged 50 and over say they are fulfilled, with just half of 25-31 year olds saying the same.
Satisfaction levels peak at 90%-plus among the oldest age group of 65 and over, said Vodafone.
The report gives a a stark warning for those employing the characteristically optimistic "Generation Y" (those born after 1980).
One of the biggest issues facing British business over the next 10 years, said Vodafone, could be the "inevitable" disillusionment that will hit these youngest members of the workforce as they start to reach their 30s.
Nick Rand, associate director of Opinion Leader, one of the companies that carried out the research, said, "The common prediction associated with Generation Y is that it is using developments in technology and new forms of communication to change working cultures forever.
"Our research showed that this young cohort is indeed highly ambitious and wants to succeed in a shorter time span than ever. But with these new, higher expectations comes the risk of greater disappointment."
He said, "The findings from our cross-generational workshops demonstrate clearly that these predictions do not take account of a feeling of mid-career depression brought on by the pressures of the family life stage."
This consensus, he said, did not only come from those currently in their early 30s, but also from those more contented workers in their 40s, 50s and 60s, who have emerged on the other side. By most, it is seen as inevitable."