In particular, Martin Seligman, deepens the studies on flow, considered as one of the main elements for a fulfilling life (engaged life) and rich in meaning (meanigful life).
The Flow experience is characterized by a high level of concentration and participation in the activity, by the balance between the perception of the difficulty of the situation and the task (challenge) and personal skills (skills), by the sensation of temporal alteration, (the internal clock slows down, while the external clock speeds up), gives an intrinsic interest in the process that produces a sense of pleasure and satisfaction.