Happiness takes work. Changes in life circumstances like a promotion or a new relationship might result in a temporary happiness boost, but before long the excitement levels off.
The Building Happiness (Exercises) worksheet includes a list of activities that have been found to help build sustained happiness, when practiced regularly. The exercises that are described include gratitudes, acts of kindness, physical exercise, meditation, positive journaling, and fostering relationships. Discuss these exercises with your client, practice them in session, and create a plan to practice a little bit every day.