The landscape of technology is rapidly evolving, and its pace of growth is not slowing down. During the last decades, and especially after the mass adoption of the internet, new technological advances have revolutionized every aspect of human life. We are living in the ubiquitous computing era, where connected devices form the internet of things and produce data faster than we can logically process. The goal of this thesis is to propose new algorithms, methodologies, and applications that can be used as components in health and wellbeing systems that support healthy aging, enhance human-machine interactions, and support postoperative rehabilitation with the use of machine learning techniques.