“…Kirkcaldy et al (2002) carried out a cross-sectional research and investigated a sample of 988 adolescents; according to the data obtained, regular practice of endurance exercises can be related to a more favorable self-image, the type of personality that tends to be resistant to drug and alcohol addiction, scores for psychological and physical well-being (characterized by lower scores of anxiety-depression and exhaustion), as well as the characteristics of social involvement and interaction, indicating that positive social feedback/recognition from peer groups can in turn improve an individual's self-image. Crone, Smith, and Gough (2005) reported findings from a quantitative investigation of a focus group that consisted of 18 mentally healthy adult participants and provided a conceptual framework of a psychosocial explanation for the relationship between physical activity and mental health where the core category is self-acceptance (self-assurance, confidence) including the factors of the context in which people exercise (social network and support, the physical environment, culture) that are important aspects of the exercising experience that can help to forecast whether exercise referral schemes have potential to influence mental health. Biddle and Mutrie (2008, p. XIV) in the preface of their book noticed the ''increase in the study of physical activity and health from a psychological point of view which can be illustrated by the number of metaanalytic reviews in the subfield of physical activity and mental health.''…”