The mattresses in the guest bedroom are too hard, I told my parents.

“They are not hard,” Dad said. “They are firm.”

“Well, they are too firm,” I said.

Mom said that maybe they weren’t broken in yet.

“When did you buy them?” I asked.

Thirty years ago, she said.

“I think they are broken in,” I said.

I understand my parents’ Greatest Generation frugality. Dad was in high school during World War II when gas and milk were rationed. My mom’s family had chickens so they ate eggs every day. Now and again they would eat a chicken. But you couldn’t eat too many chickens or you wouldn’t have any eggs, she said.

We know the mattresses are almost three decades old because my father has a habit of writing the purchase date on everything he buys from mattresses to rugs to trash cans.

Dad had scribbled August 1993 on the label. They bought the beds at Brielle Furniture. It was from the Belaire Collection made by Shifman Mattress Co.

According to the Sleep Foundation, mattresses should be replaced every six to eight years.

Dad said he extended the life by flipping and rotating the mattress according to a schedule. A few years ago I found a paper wedged under the mattress with a diagram and the dates of the rotation schedule.

Frugality is a virtue, but I appreciate that my parents aren’t caught in what the financial writer Morgan Housel calls “frugality inertia.” That’s when people save all their lives and cannot make the transition to enjoying their money.

After being persuaded that the mattresses were indeed too “firm,” my parents went online and ordered a new Zinus mattress.

Bed technology has changed a fair amount in the past thirty years.

My parents were surprised that beds no longer required box springs and that they are delivered in a box with something called a bunkie board.

The new mattresses arrived and they laid them out in the two single bed frames in the guest bedroom.

Unlike the new mattress, no one would argue that the bed frames needed to be broken in.

They were almost 100 years old.

My Dad and his brother slept in them growing up in the 1930s.

Some things apparently never wear out.

(Part of a series of life lessons based on conversations with my parents.)