Broadly, the objective of the research is to evaluate the effectiveness of a specific breathwork program (Les Mills Breath) on various physiological variables related to running performance, compared to a mindfulness control (20 minutes of guided meditation). There are three specific research questions: 1) Does daily participation in a 20-minute breathwork program improve respiratory function more than a mindfulness control intervention? 2) Does daily participation in a 20-minute breathwork program improve heart rate variability (an indicator of parasympathetic nervous system activity which is associated with enhanced exercise recovery) more than a mindfulness control intervention? 3) Does daily participation in a 20-minute breathwork program increase self-selected running speeds at relative moderate and vigorous intensities more than a mindfulness control intervention? The intended outcomes of the current research are to contribute to the field of research which has examined various forms of "respiratory training" and their effects on athletic performance, specifically running. While certain training protocols have been shown to be effective, there are issues of accessibility which persist. Methods of respiratory training/breathwork which are more easily available to recreational athletes are understudied with regards to running performance, hence the current research.