Predicting Habitual Use of Wearable Health Devices Among Middle-aged Individuals With Metabolic Syndrome Risk Factors in South Korea: Cross-sectional Study - Jaeyoung Ha; Jungmi Park; Sangyi Lee; Jeong Lee; Jin-Young Choi; Junhyoung Kim; Sung-il Cho; Gyeong-Suk Jeon (JMIR Formative Research, 2023)