Schizophrenia and bipolar disorder are among the most serious mental illnesses, and mental healthcare has yet to fully embrace digitalization. In this paper, we present action research involving twenty-one individuals who wore wearable devices for a six-week period exploring how wearables can be integrated into mental health for enhanced empowerment through a patient-centered approach. We illustrate the insights that data from wearables (e.g. heart rate, sleep, and movement) can provide for individuals with schizophrenia and bipolar disorder. Our three-fold contribution shows: (i) that self-efficacy (the belief in own ability to succeed) is an important stepping stone for empowerment, (ii) the need to focus on individual patterns when engaging with individuals with serious mental illnesses, rather than relying on group-based approaches that define more generic behavioral patterns, (iii) the dire need for IS researchers to study personal datafication in situ, through case-based, data-driven approaches to promote human flourishing in health IS.