What does it mean that calligraphy is happy, healthy and long?

This is a famous couplet, which talks about the benefits of learning calligraphy and encourages people to practice calligraphy more.

The whole sentence means that practicing calligraphy can not only refresh your mind and calm down, but also make you happy, beneficial to your body and mind, and make people healthy and live longer.

In addition, I personally like calligraphy and have personal experience. This process is to take out my treasured brush and inkstone, grind some ink leisurely, and write a long scroll on rice paper. The font is magnificent and the ink is flowing. In this idle trip, I got a vibrant body and a happy mood.