Positive emotions, identity–existential dimension, “mind-expansion” effect, and environmental factors: a pilot study on a sample of skyrunners.: Part one: theoretical background. PSE [Internet]. 2025 Dec. 17 [cited 2026 Jul. 1];3(1). Available from: https://www.ledijournals.bdtopten.com/index.php/pse/article/view/3067