Flexible, wearable, and implantable electronic sensors have started to gain popularity in improving the quality of life of sick and healthy people, shifting the future paradigm with high sensitivity. However, conventional technologies with a limited lifespan occasionally limit their continued usage, resulting in a high cost. In addition, traditional battery technologies with a short lifespan frequently limit operation, resulting in a substantial challenge to their growth. Subsequently, utilizing human biomechanical energy is extensively preferred motion for biologically integrated, self-powered, functioning devices. Ideally suited for this purpose are piezoelectric energy harvesters. To convert mechanical energy into electrical energy, devices must be mechanically flexible and stretchable to implant or attach to the highly deformable tissues of the body. A systematic analysis of piezoelectric nanogenerators (PENGs) for personalized healthcare is provided in this article. This article briefly overviews PENGs as self-powered sensor devices for energy harvesting, sensing, physiological motion, and healthcare.