Inclusion Criteria:  Studying in secondary grades one to three Between 12 and 15 years old Belongs to a family with a household income below half of the median household income reported in HK, which was adjusted by household size  Exclusion Criteria:  Hypertension or diabetes mellitus without control A history of brain injury and other neurological disease, epilepsy, or myocardial infarction Musculoskeletal disease Use medication that affects heart rate (e.g., beta-blockers, asthma medications, stimulants, digoxin, antiarrhythmic agents) Cardiovascular disease