Our Western society is characterized by multitasking, competition, and constant time pressure. Negative effects of stress
for the individual (anxiety, depression, somatic complaints) and for organizations and society (costs due to work absence)
are very high. Thus, time-efficient self-help interventions to address these issues are necessary. This study assessed the
effects of daily mindfulness meditations (MM) versus daily heart rate variability biofeedback (HRV-BF) and daily physical
exercise (PE) on attention control, executive functioning, mindful awareness, self-compassion, and worrying. Young adults
(n = 75, age range 18 to 40) with elevated stress levels were randomized to MM, HRV-BF, or PE, and measurements were taken
at pre-test, post-test, and follow-up. Interventions in all three groups were self-guided and lasted for 5 weeks. Generalized
estimating equation analyses showed that overall, all three interventions were effective and did not differ from each other.
However, practice time differed between groups, with participants in the PE group practicing much more than participants in
the other two groups. Therefore, additional analyses were carried out in two subsamples. The optimal dose sample included
only those participants who practiced for at least 70 % of the total prescribed time. In the equal dose sample, home practice
intensity was equal for all three groups. Again, the effects of the three interventions did not differ. In conclusion, MM,
HRV-BF, and PE are all effective self-help methods to improve attention control, executive functioning, mindful awareness,
self-compassion, and worrying, and mindfulness meditation was not found to be more effective than HRV-biofeedback or physical
exercise for these cognitive processes.