Happiness is a state of activity.

Now to exert oneself and work for the sake of amusement seems silly and utterly childish. But to amuse oneself in order that one may exert oneself, as Anacharsis puts it, seems right; for amusement is a sort of relaxation, and we need relaxation because we cannot work continuously. Relaxation, then, is not an end; for it is taken for the sake of activity.

Happiness is activity.

Happiness involves engagement in activities that promote one's highest potentials.