The human body produces a huge amount of energy while performing daily activities. Harvesting this energy could represent a turning point for powering wearable devices. Advances in physical and chemical fields enable the design of flexible and stretchable materials that adhere to the surface of the body to follow the shape of the skin. Functional polymeric fibers allow the development of smart-clothes for harvesting the energy on the surface of the human body. Humans generate remarkable quantities of energy while performing daily activities, but this energy usually dissipates into the environment. Here, we address recent progress in the development of nanogenerators (NGs): devices that are able to harvest such body-produced biomechanical and thermal energies by exploiting piezoelectric, triboelectric, and thermoelectric physical effects. In designing NGs, the end-user's comfort is a primary concern. Therefore, we focus on recently developed materials giving flexibility and stretchability to NGs. In addition, we summarize common fabrics for NG design. Finally, the mid-2020s market forecasts for these promising technologies highlight the potential for the commercialization of NGs because they may help contribute to the route of innovation for developing self-powered systems. Humans generate remarkable quantities of energy while performing daily activities, but this energy usually dissipates into the environment. Here, we address recent progress in the development of nanogenerators (NGs): devices that are able to harvest such body-produced biomechanical and thermal energies by exploiting piezoelectric, triboelectric, and thermoelectric physical effects. In designing NGs, the end-user's comfort is a primary concern. Therefore, we focus on recently developed materials giving flexibility and stretchability to NGs. In addition, we summarize common fabrics for NG design. Finally, the mid-2020s market forecasts for these promising technologies highlight the potential for the commercialization of NGs because they may help contribute to the route of innovation for developing self-powered systems. electronic components manufactured by major international companies for the consumer electronic market. the process by which the wasted energy from environmental sources is recovered and stored for powering electronic systems or to prolong their operation time. specialized materials that use their structural properties to perform specific tasks. a structure, almost 1D, which is cylindrical or polyhedral with nanometric dimensions. Many different types of NW exist, including superconducting, metallic, semiconducting and insulating NWs, fabrics that detect external stimuli and react according to the surrounding environmental conditions.