The aim of the study reported in this paper was to explore the issues of motivation of student teachers before and after their two practicum blocks which were held in the third and final years of teacher training. Participants provided quantitative and qualitative data through questionnaires and in-depth interviews which were conducted at four time-points over two years: pre-practicum and post-practicum in the third and final years of studies. This study adopted mixed methods to collect data--questionnaires, in-depth interviews and weekly log entries. Results showed that the origins of student teachers' worries were originated from different aspects, of which some later became the sources of motivation. The four longitudinal qualitative cases herein demonstrate how student teachers sources of motivation change over time.