There are many research projects focused on pre-service teachers' professional development programmes but only a few focus on mid-life career-changing teachers' career decision. This paper worked with data collected from semi-structured interviews with 11 mid-life career-changing secondary school teachers. The aim was to understand the career decisions of these participants and how they made sense of their new profession during their mature adulthood in Indiana, USA. 11 mid-life career-changing secondary school teachers referred to 'changing the next generation with industry experience', 'rich life experience', 'life-long learning', 'knowledge transferring', and 'make a difference' to describe their current occupation as career changing secondary school teachers. The findings also outline how to reform the curriculum and instruction of the pre-service teachers' professional development programmes.