He said it was possible that he could become bored with retirement, and want to work again.
"But I sure don't feel that way now," Guenther said. "I don't want to do anything. This is pretty cool."
Guenther is among the first wave of baby boomers Americans born between 1946 and 1964 who have reached traditional retirement age and wasted little time before saying goodbye to the working world.
It's a group that a new study by MetLife Inc says so far has defied the popular belief that baby boomers will be working longer than planned because their retirement savings got trashed in the stock market downturn.
"Despite the conventional wisdom that boomers are ready to 'work forever' and significantly extend their formal working career, many of the oldest boomers are already well into the retirement phase," the study says.
The MetLife study is a follow-up to a 2008 report that looked at the same segment of boomers at age 62, and includes 450 of the same interview subjects from the original study.
The study says 59 percent of the first boomers to turn 65 are at least partially retired. Forty-five percent are completely retired, and 14 percent are retired but working part-time.
Of those still working, 37 percent say they will retire in the next year and, on average, plan to do so by the time they're 68. Almost 63 percent already are collecting Social Security retirement benefits.
Almost all of the retirees 96 percent said they like retirement at least somewhat, and 70 percent like it a lot.
Kelli B. Send is not surprised by the apparent eagerness of baby boomers to retire.
"I just don't see a lot of people stay beyond 65, even though they say that's going to be the trend," said Send, who as senior vice president for Pewaukee, Wis.-based Francis Investment Counsel talks regularly with individual workers about managing their 401(k) plans at companies that are clients of her firm.
She said workers insist they want to retire by 65 even those who wouldn't appear to have enough money saved up for it.
"I think what they're saying to themselves is, 'You know, I may not have the standard of living that I once could, but I'm going to retire anyway because I'm sick of working, and I'll just figure out a way to make it work,' " she said.
She said many people seem to believe that once they become eligible for Medicare at 65 and start getting Social Security payments, they'll "make the rest of the math work."
It's too soon to know whether that optimistic approach will be successful in reality for the first boomer retirees, but there's reason to be skeptical.
A survey last year by the mutual fund company Vanguard found that the average 401(k) retirement plan balance for those 65 and older was about $163,000.
"There's a rule of thumb that you can pull out about 5 percent of your money a year some advisers will tell you 4 percent but in the range of 4 percent to 5 percent," Send said. "So for every $100,000 you've got put away, it buys you an income of $5,000."
Even with Social Security and a pension payment if there is one that seems likely to mean some serious lifestyle adjustments for those who haven't saved enough.
Last year, a study done for The Wall Street Journal found that the median household headed by a person 60 to 62 with a 401(k) account has less than one-quarter of what is needed in that account to maintain its standard of living in retirement.
Nonetheless, Send said a recurring theme she hears during her sessions with rank-and-file employees is that many yearn for "life after work."
"I think so much of it is that people have worked their whole life and they've got things they want to do, and they'd like to hurry up and get doing them," she said.
Among retired respondents in the MetLife study, which surveyed 1,012 people born in 1946 and had a 3 percent margin of error, the biggest reason by far given for retiring was simply, "Reached retirement age/wanted to."
J. Bernard Fiedler, president of wealth management services for Waukesha (Wis.) State Bank, said saving for retirement is "a 20- or 30-year hitch," and it takes planning to make the post-working years comfortable.
"You've got a division between people who have planned and they're set, and those who flat-out just stick their head in the sand," Fiedler said.
Fiedler said one unfortunate surprise for those who haven't saved enough and expect to keep working beyond 65 or realize they need to go back to work after they retire is that employers don't necessarily want them back.
The unemployment rate remains high, and many companies have spent the past few years offering buyouts to entice older or higher-paid employees to quit.
In the MetLife survey, a third of those still working said they have decided to delay retirement, mainly because they need to continue receiving a salary to pay for day-to-day expenses.
The study also says the average age at retirement for those who have already stopped working was 59.7 for men and 57.2 for women.
Send says she's found that for many boomers, the delay in retirement has been not so much putting it off to 67 or later, but rather, putting it off until 65 from 62, which is when they really had hoped to hang it up.
"They say, 'My goal before the market tanked and before everything happened was to be done at 62,' " Send said. "The goal, for the most part, is being recalibrated to 65. It's really much more about that."