Enjoyment appears at the boundary between boredom and anxiety, when the challenges are just balanced with the person's capacity to act.

ISBN 0-06-092192-7
Csikszentmihalyi Mihaly (1996). Optimal Experience: Psychological studies of flow in consciousness Cambridge: Cambridge University Press. "
To achieve a flow state a balance must be struck between the challenge of the task and the skill of the performer.

He is noted for his work in the study of happiness and creativity but is best known as the architect of the notion of flow and for his years of research and writing on the topic. iː/ MEE-hy CHEEK-sent-mə-HY-ee; Hungarian: Csíkszentmihályi Mihály [ˈtʃiːksɛntmihaːji ˈmihaːj]; born September 29 1934 in Fiume Italy – now Rijeka Croatia) is a Hungarian psychology professor who emigrated to the United States at the age of 22. Martin Seligman former president of the American Psychological Association described Csikszentmihalyi as the world's leading researcher on positive psychology.