Narrator: This is Science Today. A leading psychiatrist at the University of California, San Francisco says adults should continue to play well past their childhood to attain fulfillment and balance in their lives. Dr. Lenore Terr says playing is defined as any activity done just for the fun of it, but she cautions couch potatoes that time in front of the TV is not truly play.

Terr: To be a couch potato, one goes into a state of consciousness which we probably all need - which is to just blank out and forget everything and just have peace. But that is not the same as play. Play requires super concentration.

Narrator: So long as this super-concentration is involved, any activity - whether mental or physical - can be considered play.

Terr: All of us have different ways of playing because we're built different ways. Some of us are real sports people; we're built athletically. Some of us are real chess players. So, we tend to play in the ways that are most natural - the most easy for us.

Narrator: For Science Today, I'm Larissa Branin.