Relaxation was an emotional state of low tension, or a lack of arousal, especially from negative sources like fear, anxiety, or anger.
In 2374, Captain Kathryn Janeway tried to illustrate to Seven of Nine the importance of relaxation and artistic expression by having her sculpt a head made out of clay in the Leonardo da Vinci's workshop holographic program. Seven seemed to find the exercise to be unproductive. (VOY: "The Raven")