The literature has shown that heart rate variability, a direct expression of the interaction between the sympathetic and parasympathetic nervous systems, is one of the most reliable measures of emotion regulation skills. Studies on this topic have also stressed that relaxation techniques influencing heart rate variability are able to promote an increase in psychological well being. It is less clear, however, the extent to which individual differences in emotion regulation may affect the outcome of using these relaxation techniques. The aim of this pilot study is to evaluate if the capacity to regulate emotions of individuals undergoing a brief training in breathing can have an effect on the outcome of the training itself. The results show different patterns, and suggest that the individuals who benefit more from the training are those who at baseline appeared to show more difficulties in emotion regulation.