Since the inception of the L2 motivational self system (Dörnyei, 2005), which operationalises motivation as a function of learners' future identities, the field of L2 motivation has seen a growing interest in mental imagery. Numerous studies have examined the role of a future self-guide, that is, the ideal L2 self, and have confirmed it to be powerful for explaining learner motivation (e.g., Csizér & Lukács, 2010; Dörnyei & Ushioda, 2009); however, few studies have explored how mental imagery, a key dimension of the ideal L2 self (Dörnyei & Chan, 2013), can manifest itself in actual motivated behaviour. Using in-depth interviews, the present study aims to explore the motivational capacity of the natural use of mental imagery in three doctoral candidates studying at a British university. The main research focuses on examining how imagery was employed to stimulate the participants' L2 learning and their doctoral research as well as career choice. This paper proposes a conceptual framework of types, functions, and conditions of imagery in academic and professional achievements based on the data obtained. It reveals an intriguing array of imagery types, functions, and conditions, which shape the achievement of the individuals' desired goals. Recommendations and implications for future research on imagery use in SLA are also discussed.