The leitmotiv of my research is the psychophysiological study of individual differences in behaviour and health. Controlled experiments and genetic epidemiological strategies are used to test contribution of genes, stress and regular exercise to cardiovascular health and mental health. Mental health is studied by a variety of survey measures and diagnostic interviews. Cardiovascular health is studied in the laboratory by recording cardiovascular, hormonal and metabolic responses to standardized conditions, and in “real life” by using ambulatory measurements of blood pressure, cortisol, and the autonomic nervous system with the VU University Ambulatory Monitoring System (VU-AMS, www.vu-ams.nl). This is a system that I developed for 24-hour recordings of peripheral physiology to study stress and emotion in naturalistic settings. In the study of mental and cardiovascular health a genetic perspective is introduced by means of longitudinal twin family designs and molecular genetic approaches, including whole-genome association using SNPs or CpGs. The causes and consequences of stress and regular exerciser behaviour are current areas of research interest. In these areas I emphasize the gene-environment correlation and interaction perspectives, e.g. by looking explicitly also at gene-stress and gene-exercise interactions, and the use of genetically informative prospective studies to unravel causality, e.g. between regular exercise and mental health.