The potential benefits of workplace wellness programs are limited by low participation rates of employees, which could be due in part to ineffective persuasion by program providers. This study uses the Elaboration Likelihood Model, as a guiding theory in mixed methods research, to investigate feedback messages about physical activity delivered in a workplace wellness program. This study uses questionnaire and interview data from 32 employees to determine if personally relevant health messages are associated with either positive or negative responses to the messages and subsequent attitude change. General feedback is more appreciated by those who are less fit but are not effective in changing attitudes toward physical activity. Individually targeted messages result in a significant positive attitude change for participants responding positively to the messages. This suggests that individualized health promotion messages provide a stronger argument for individuals, thus increasing the likelihood of attitude change.