Boredom kicks in after just 10 months of retirement, according to Skipton Building Society research.
More than half of those surveyed (54%) said the retirement glow wore off because they missed the camaraderie they had at work, while four in 10 felt they weren't being mentally stimulated enough at home.
More than a third admitted their days had become repetitive and 20% felt completely redundant.
A further 19% said daytime television is awful, and 24% complained the great British weather puts a stop to them getting out and about.
Meanwhile, 14% felt taken for granted a little by their families, who expected them to happily become babysitters to their grandchildren.
Lack of disposable income – 31% struggled to cope without their monthly wage packet – irritating partners putting on weight due to inactivity were other reasons cited for disillusionment with retirement.
However, there were many people enjoying advantages to retirement. During the first few weeks of retirement a third of people went on holiday and 23% took time out to get the house sorted by having a big clear out.
Buying a new car, taking up a new hobby and spending more time with friends and family were all listed as benefits of retirement.
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Stacey Stothard, spokesperson for Skipton Building Society, said: "Despite anticipating retirement for a greater part of their working life, our study shows that many people struggle to adjust to a new existence that's free of structure. Some feel unproductive or that they're wasting their accumulated career knowledge. Ten months in and many feel their retirement isn't as good as they thought it would be."
So what makes the transition easier?
The Skipton survey found that two thirds of retirees said having plenty of money makes life less troublesome, while 84% said good health counts for a lot. Living near friends and having plenty of hobbies were said to help too.
Stothard added: "People retire from work, not life. And while the fresh novelty of being newly retired may fade, many retirees have found that by challenging themselves, finding new forms of enjoyment, learning new things, and having ambitions, can all help ensure you're as busy and stimulated in retirement as you were in work."
Top reasons retirees get disillusioned
1. I missed the camaraderie I had at work
2. The novelty of not working wore off
3. I was bored
4. My mind wasn't being pushed
5. I didn't have as much disposable income as I thought
6. The glow just wears off because you get used to it
7. When everyday ended being the same as the day before
8. I didn't have many friends who had retired
9. The nice weather ended and I had t spend more time indoors
10. I was lonely