There is now strong evidence of a relationship between sedentary behaviour (SB) and deleterious health outcomes, including mortality (Katzmarzyk & Lee, 2012) and cancer (Lynch, 2010). Such findings have been cause for concern, and intervention is an increasingly popular topic. However, social-cognitive theory suggests that behaviour change is not as simple as saying “stop!” – it requires both self-regulatory abilities (the “how”) and motivation (the “why”). Past work (Gierc & Brawley, 2014) indicates that laypersons define SB differently than researchers, and that perceptions of SB vary by context/activity (e.g., socialising over video games versus coffee). If health interventionists make SB risk statements, (1) will these reflect individuals’ own view of risks, and (2) will these risks motivate behaviour change? The current study examined individuals’ perceived risks and benefits of SB engagement. 152 participants completed an online mixed-methods survey on SB activities and risk/benefit perceptions. Qualitative data was inductively analysed, and response frequencies calculated. Participants identified many characteristically-sedentary activities, with more respondents focussing on leisure (e.g., watching television, 80.9%) than work (office jobs, 34.2%) and transportation (25.7%). Risk/benefit analysis revealed nine major benefits of SB, including rest/relaxation (51.3%) and positive moods (13.8%). Eleven major risks were identified, including reduced fitness (40.1%) and negative emotions (15.1%). Results carry three implications. First, while individuals can identify many different types of SB, responses were primarily directed toward leisure-time pursuits versus other life domains (e.g., work). Second, the perceived risks of SB in this layperson sample (e.g., fitness, stress) differ from conditions commonly identified by health research investigators (e.g., cardiometabolic disorders). Third, individuals also associate SB with positive mental and physical outcomes. Findings highlight the need for sedentary psychology research, such as determination of whether the pursuit of favourable proximal SB outcomes will interfere with intervention efforts that target distal physical health risks.