The study focuses on targeting overweight, stress, and impaired overall wellbeing with new cost-effective intervention methods. The intervention methods are based on the principles of cognitive behavioural therapy (CBT) and further acceptance-commitment therapy (ACT). The interventions are delivered either face-to-face, via mobile application, or via Internet. The purpose of each intervention is to improve the subjects lifestyles and activate them towards beneficial changes in their everyday life. The psychological and physiological effects of interventions are measured with various invasive and non-invasive methods. The study gives new insight into effectiveness and acceptability of up-to-date psychological intervention methods, and new knowledge of different ways to deliver interventions for improving wellbeing of an individual.