Fig. 2

Screenshots of the instruction and feedback of the relaxation exercise. MT-StressLess with HR-based biofeedback condition included a relaxation exercise. Participants were asked to identify a typical stress situation and to choose a body posture for the exercise (left). They were then asked to hold their smartphone near their heart during the audio instruction (middle). Participants were then shown their HR during the relaxation exercise and given motivational feedback, depending on how the HR decreased during the relaxation phase (right).