Conceptualizing learners' individuality as dynamic and contextually situated, this paper reports on an inquiry that examined the genesis of a disabled learner's success in learning foreign languages on the Chinese mainland. Using source texts such as the learner's published diaries, letters and her autobiography, the inquiry revealed that language learning success could be explained by her unwavering will, unyielding beliefs and tenacious efforts in learning languages. Her narratives further unveiled the role that contextual conditions and the learner's agency played in shaping and reshaping her motivational discourses, learning beliefs and strategic efforts. These findings help illustrate how these crucial individual difference factors interact with each other in the language learning process. They also provide further food for thought for language learners and teachers in their efforts to identify means that sustain autonomous language learning efforts in difficult conditions. (Contains 1 table.)