This study aims to enhance second language (L2) learners' motivation and facilitate successful L2 learning by using motivational languaging, an intervention that encourages learners to reflect on, and externalize, their L2-speaking, competent future self-concepts by writing or speaking about them. Two types of effective languaging activities were developed: individual and group writing. Participants were 264 Grade 10 high school students, divided into three groups: one control group and two experimental groups. Using activity workbooks, the first experimental group engaged in 'individual writing' guided by a series of questions in their workbooks (e.g. reasons for learning English and their ideal images of using English). The second experimental group carried out 'group writing', including group discussions and writing of group members' opinions. The activities were conducted in the participants' first language, Korean, for 30-40 minutes once a week for six weeks. The results indicated, in the two experimental groups, that the participants' L2 learning motivation was enhanced, including the ideal L2 self. When observing the changes in the influence of motivation on motivated L2 learning behavior and English proficiency, meaningful increases were only found in the individual writing group, with the ideal L2 self showing more powerful impact on the two criterion measures after the activities.