The paper proposes a new conceptual perspective for understanding students' engagement in L2 learning, in particular the concept of interest development in learning English. It investigates situational features that trigger interest in learning English, employing data from interviews with non-native English speaking students studying in TESOL programmes. Students were invited to reflect on critical moments which triggered their interest in learning English. These events were discussed in terms of three temporal stages: sources of interest in early years (primary), in teenaged years (secondary) and in adulthood (university and work). The findings show that what triggers interest is not just the ability to imagine and predict the vision of the future but the reimagining or revisioning of the past or one's ability to postdict the past event in accordance with the present experience. It is not just the value of English (i.e. a property of topic or topic interest) per se that triggers interest but how its value is presented and experienced. For interest to be triggered, English must be presented or experienced in such a way that it creates surprise, unexpectedness, and encourages post-hoc understanding of the importance of English and one's past interaction with English. (Contains 1 table.)