Inclusion criteria:  aged 21 to 69 years of age citizen or permanent resident of Singapore of Chinese, Malay, or Indian ethnicity able to read English own or have continued access to a smartphone with a data plan able to use smartphone apps able to walk independently  Exclusion criteria:  history of stroke, heart disease, renal failure, diabetes mellitus, thyroid disease, cancer, or a serious mental health condition (e.g., schizophrenia, depression, or dementia) have had vascular bypass surgery or angioplasty procedure performed known sensitivity to medical-grade adhesives bleeding disorder