This paper explores strategies employed by amateur triathletes engaged in serious leisure to negotiate leisure constraints. In-depth interviews were conducted with 21 Australian triathletes, revealing a range of negotiation strategies used to adapt to or alleviate constraints. In particular, triathletes accepted the likelihood of opportunity costs, were pragmatic about their performance and used a self-determined hierarchy of importance to make leisure/non-leisure decisions. They engaged in planning and time management, endeavored to communicate and cooperate with significant others, were opportunistic and flexible with training, and employed discipline props to maintain participation. Their participation was cyclical in nature, with periods of intense involvement before events. Cognitive and behavioral negotiation strategies were interconnected, suggesting implications for physical activity programs and interventions.