Parents quickly learn that saying “don’t” is a sure way to make sure children “do.”

For example, “don’t jump on the bed again,” is just about guaranteed to send Johnny jumping on the bed — and sliding down the bedpost in his best fireman imitation.

Instead, the experts say, parents should offer positive reinforcement for behaviors they like — and which earn their approval.

“Stay on the ground” or “sit still while you’re on that bed” are much favored over the “don’t-do-thats.”

And, like most important rules in life, this early childhood lesson apparently holds true no matter what your age.

A study published this week in the Journal of the American Geriatrics Society argues that reinforcing elderly people with positive messages and images — “wise” instead of “weathered” or “astute” instead of “dependent” — can actually help them pick up their pace.

It seems the elderly residents involved in the study actually walked a little bit faster, and shuffled a little bit less, when they were exposed to positive words and descriptions — 9 percent faster than those exposed to the negative words.

Is it really that simple?

We think it is.

In a society filled with criticism and failed perfectionists always striving to be a little bit better, a little bit richer, a little bit smarter, we often forget to stop and take inventory of the things others do well. And, moreover, we often forget to stop and listen to ourselves — to take an inventory of our words to see if they are encouraging or disparaging.

Now, science is telling us that those words can make a measurable difference on our lives and the lives of our loved ones — at any age.

We should remember the power of our words … to help and to heal.