With circulatory pathology, patient-specific simulation of hemodynamics is required to minimize invasiveness for diagnosis, treatment planning and follow-up. We investigated advantages, obtained by smart combination of often already known hemodynamic principles. The CircAdapt model was designed to simulate beat-to-beat dynamics of the 4-chamber heart with systemic and pulmonary circulation, while incorporating a realistic relationship between pressure-volume load and tissue mechanics, and adaptation of tissues to mechanical load. Adaptation was modeled by rules, where a locally sensed signal results in a local action of the tissue. The applied rules were: a) for blood vessel walls: 1) flow shear stress dilates the wall, 2) tensile stress thickens the wall, and b) for myocardial tissue: 3) strain dilates the wall material, 4) larger maximum sarcomere length increases contractility, and 5) contractility increases wall mass. The circulation was composed of active and passive compliances and inertias. Providing mean levels of systemic pressure and flow, a realistic circulation developed by self-structuring through adaptation. Ability to simulate a wide variety of patient specific circumstances was demonstrated by application of the same adaptation rules to the conditions of fetal circulation, followed by switching to the newborn circulation around birth. It was concluded that a few adaptation rules, directed to normalize mechanical load of the tissue, were sufficient to develop and maintain a realistic circulation automatically. Adaptation rules appear the key to reduce dramatically the number of input parameters for simulating circulation dynamics. The model may be used to simulate circulation pathology and to predict effects of treatment.