Energy harvesting has been among the most discussed topics over the past decade in the context of autonomous systems and the Internet of Things (IoT). In this paper, we present an up-to-date review of kinetic energy harvesting techniques. In particular, we look into the requirements for wearable applications and the progress in energy harvesting in relation to such applications. We start by discussing the fundamental limits on the energy available from ambient kinetic energy sources. We then provide a review of recently proposed electromechanical devices intended for electromechanical energy conversion using the electrostatic mechanism. Finally, we discuss the design of a kinetic energy harvester at the system level.