Aim: Motivation to take up and maintain a healthy lifestyle is key to diabetes prevention and management. Motivations are driven by factors on the psychological, biological and environmental levels, which have each been studied extensively in various lines of research over the past 25 years. Here, we analyse and reflect on current and emerging knowledge on motivation in relation to lifestyle behaviours, with a focus on people with diabetes or obesity. Structured according to psychological, (neuro-)biological and broader environmental levels, we provide a scoping review of the literature and highlight frameworks used to structure motivational concepts. Results are then put in perspective of applicability in (clinical) practice. Results: Over the past 25 years, research focusing on motivation has grown exponentially. Social–cognitive and self-determination theories have driven research on the key motivational concepts ‘self-efficacy’ and ‘self-determination’. Neuro-cognitive research has provided insights in the processes that are involved across various layers of a complex cortical network of motivation, reward and cognitive control. On an environmental – more upstream – level, motivations are influenced by characteristics in the built, social, economic and policy environments at various scales, which have provided entry points for environmental approaches influencing behaviour. Conclusions: Current evidence shows that motivation is strongly related to a person's self-efficacy and capability to initiate and maintain healthy choices, and to a health climate that supports autonomous choices. Some approaches targeting motivations have been shown to be promising, but more research is warranted to sustainably reduce the burden of diabetes in individuals and populations.