In this study, Japanese university students learning English in Japan were asked to keep a confidence-building diary (CBD) for one week in order to understand the benefits of maintaining a positive outlook for learning. The researchers investigated what activities the participants engaged in and what emotions they felt as a result, how the activity influenced their motivation for learning English and also whether participants later continued to engage in confidence-building activities. Drawing on basic psychological needs theory, self-determination theory, research on effect in language learning, and positive psychology, the researchers conducted a qualitative analysis of the diaries of 39 participants. The researchers also conducted follow-up interviews approximately five months later with seven participants. Participation in the CBD activities resulted mainly in positive emotions, occasionally in combination with negative emotions, and supported basic psychological needs. All participants considered the activity to be worthwhile, and there was evidence that some participants continued to intentionally engage in activities that produced positive emotions as a result of the CBD activity. The researchers suggest that the CBD is an effective tool for promoting positive feelings and supporting students’ basic psychological needs which are necessary to thrive and maintain motivation for sustained learning.