If you want to know how things might turn out — whether trying a new restaurant or making a mid-life career change — ask those who’ve gone before you. That’s what the Wall Street Journal did recently in order to help pre-retirees (which is all of us who are still working) prepare for their post-career lives.

While the findings were more qualitative than quantitative, they still offer a helpful sneak peak at the future. Many of the retirees who sent feedback to the Journal said they’ve experienced numerous financial surprises—some pleasant, and some not so pleasant.

So far so good

Several retirees said one of their most pleasant surprises was that their finances were holding up so well. Still, they were mindful of what it took to create that reality.

Retired engineer Rick Abell said, “I’ve lived in the same house since 1972, keep cars for 10 years, exercise regularly for good health and, basically, live within my means.” If “you want to have a comfortable retirement, sacrifices are necessary while working.”

Others emphasized the importance of entering retirement debt-free. That was one of the biggest takeaways from retired physician Jonathan Stolz. “Having retired in 2004 without any money owed to the bank made riding out the stock market downturn and recession four years later easier to withstand. And I was able to sleep at night.”

That’s a message more people could benefit from hearing, as the amount of debt carried by older people is growing.

The Consumer Financial Protection Bureau (CFPB) says the percentage of homeowners ages 65 and older with mortgage debt increased from 22 percent in 2001 to 30 percent in 2011. Among homeowners 75 and older, the rate more than doubled, from 8.4 to 21.2 percent.

Also according to the CFPB, between 2005 and 2015, the number of people age 60 or older with student loan debt quadrupled to 2.8 million. That age group is the fastest-growing segment of people with student loan debt. In most cases, such borrowers took out loans for their kids’ or grandkids’ educations, or they co-signed on such loans and now find themselves responsible for the payments.

Didn’t see THAT coming

The two most unpleasant financial surprises noted by retirees profiled in the Journal were higher than expected Medicare costs and living expenses.

Some didn’t realize they might be subject to surcharges for Medicare Part B or prescription drug coverage, which can be triggered by large and/or sudden changes in income due to a buyout or the sale of stocks.

Income levels have to be fairly high (more than $170,000 for couples filing jointly) to trigger those surcharges, but for those in that situation, monthly premiums can be twice or, for especially high-income people, even more than three times as high as what lower-income people pay.

As for the cost of living, a number of retirees said rules of thumb—for example, that retirees can expect to spend about 80% of pre-retirement income—can be misleading, especially in the early years of retirement.

“The big reality is that you will spend 100% of your preretirement income after you retire,” according to Steven Fechner, a retired geologist. While you may spend less on commuting and work clothes, he said, you may more than offset those savings with larger outlays for travel, entertainment, medical expenses, and more.

The article is well worth reading in its entirety, as it also looks at surprises retirees have experienced in their relationships, how they spend their time, and how they have built a meaningful, fulfilling post-career life.

If you’re retired, what are some of the biggest surprises—financial or otherwise—you’ve experienced?