Purpose: Young adult males (YAMs) are understudied with respect to lifestyle interventions to address overweight and obesity in this group. This study reports on the participatory design of the structure and delivery of the Fit4YAMs text message–based lifestyle intervention for 18- to 25-year-old rural YAMs in Australia. Methods: Two semi-structured focus group discussions were held with six overweight or obese YAMs. Sessions explored their preferences for the structure and delivery of a weight loss intervention. Focus groups were recorded, and the contents transcribed verbatim for thematic analysis. Results: The YAMs were unanimous in their preference for a highly personalized intervention program, complete with personalized goal setting, personalized motivation and engagement strategies, and personalized text message content. A text message frequency of three–four messages per week was deemed optimal for this group. Minimal direct contact by the intervention team was requested, but with clear guidelines and reminders of key contacts whom they could contact should they require help and guidance. The YAMs also agreed that a comprehensive goal setting session and personalization session prior to commencement of the intervention would be best. Conclusions: To engage rural YAMs in lifestyle interventions, a high degree of personalization of the program appears important. Although initially more time and resource intensive than a less personalized approach, it is essential to identify strategies to prevent and reverse weight gain in this hard to engage group. Maximizing their engagement using a more personalized approach could be the key to promoting long-term health outcomes in this group.