This study expanded the State Mindfulness Scale for Physical Activity (SMS-PA) to include acceptance items to better represent core elements of mindfulness. Young adults who just participated in physical activity (N = 394) completed a survey to assess state mindfulness and theoretically relevant constructs about affect, motivation, and body image. An exploratory factor analysis was used to reduce the item pool on half of the sample. A 19-item and 15-item version of the SMS-PA2 were further tested through confirmatory factor analysis on the second half of the sample demonstrating a theoretically based factor structure representing either a total score or four separate factors -- monitoring of the mind and body and accepting of the mind and body. The SMS-PA2 scores demonstrated evidence supporting construct and incremental validity through associations with theoretically relevant variables. Initial evidence shows expanded predictive utility of the SMS-PA2.