Although low levels of stress can be motivating, high levels of stress – especially when it is sustained – can be detrimental to mental and physical health. Mindfulness practice has been widely applied in health care worldwide as an effective stress management approach. This study compared the immediate effects of two types (religious: Serenity Prayer; and non-religious: Body Scan) of mindfulness practice with a control condition (resting: sitting) in six adults. This study found no statistically significant difference between the conditions, but data visualization showed a trend of cardiovascular modulation (increased high frequency of heart rate variability) and cortical modulation (increased alpha to beta ratio and theta to beta ratio of quantitative encephalogram) with a greater level of perceived stress-relieved by both types of mindfulness practice. In addition, religious belief may be a moderator of the effects of intervention. The results of this study offered insight into the effect of prayer on cardiovascular and cortical modulation for promoting the well-being of a person.