Individuals diagnosed with myositis have skin, joint, and visceral organ involvement together with proximal muscle weakness, impaired physical function, sexual function, and quality of life also affect individuals psychosocially. Increased anxiety-depression-anxiety problems are observed in individuals, and many factors contributing to these conditions are reported. Therefore, while holistic evaluation of individuals, including these factors, gains importance, more information on how the quality of life changes during the disease is required. There is a need for tools to evaluate these characteristics in individuals disease management and treatment process. The cognitive Exercise Therapy Approach (Bilişsel Egzersiz Terapi Yaklaşımı-BETY) is an innovative exercise model based on physical exercise and an example of a biopsychosocial approach developed in patients with rheumatism. The BETY-Biopsychosocial Questionnaire (BETY-BQ) was created by repeated statistics of the improvement characteristics reported by individuals who participated in BETY sessions for many years. The BETY-BQ holistically evaluates many biopsychosocial characteristics of the individual, such as pain, coping skills, functionality, mood, sociability, sexuality, and sleep. Therefore, there is a need for scales that holistically evaluate the symptoms mentioned in myositis disease. Since the BETY-BQ can assess biopsychosocial characteristics quickly and its structure was created with the feedback of individuals with chronic disease, it aimed to examine its validation in this disease group. This study, which the investigators planned to contribute to this field, aims to investigate BETY-BQ\^s validity, reliability, and responsiveness in individuals diagnosed with myositis.