Research has shown that doing this reduces blood pressure and stress hormones, increases the feel good chemicals in the brain and creates better health in general. What is it?

A: Being kind. Performing acts of kindness.

Today's question is

The first recorded one of these goes back over 2400 years. This invention has been refined over the years and almost all of us use one every day. What is it?

Full Disclosure......we don't use it as much as we used to.