Strength training is a form of physical activity shown to provide numerous benefits, and is recommended for all adults in addition to aerobic exercise. Participation rates are low, especially with adult women. Group fitness classes may be a valuable resource for women to undertake strength training. An encouraging, knowledgeable instructor and supportive peers can facilitate skill development and internalizing values. The current study examined factors associated with women who routinely strength train. Quantitative and qualitative data was collected from women who had exercised in a group fitness setting for at least six months and were either strength training or aerobic participants. Strength training group fitness instructors were interviewed to determine correspondence to group fitness participant perceptions. Statistical analyses demonstrated significant differences in muscular development and weight management motives, and strength and aerobic activity knowledge between women who do and do not strength train. Among all women who reported using more strategies to maintain their exercise behavior, more self-determined behavioral regulation and stronger motivation for muscle development were observed. The overarching concept of trust emerged from the qualitative data. Women who strength trained described trust in their instructor and the group fitness setting, as well as trust in their body's capabilities and capacity for strength. Both groups of women described concurrent internal and external motivating factors for exercise. The focus of this study was on strength training; however, insight from women who have successfully adopted and maintained any exercise habit can be valuable for any effort designed to encourage women to initiate physical activity behaviors.