The purpose of the present study is to evaluate the clinical efficacy of belly breathing using a smartphone-based biofeedback application to reduce procedural anxiety and pain in children having their blood drawn in the blood collection lab at BC Children's Hospital. This phase of the study will focus on evaluating 1) the efficacy of the application in children ages 5-17 for reducing self--reported pain and anxiety during blood collection and 2) the ability of the application to increase belly breathing compliance and engagement compared to traditional teaching methods.