This article shares the first author's experiences at a high school in Fez, Morocco, while implementing education for sustainable development (ESD) in the curriculum. In this action research project, the researcher aimed to embed ESD in the current school curriculum and evaluate whether the strategies and methods used affected the students' attitudes and behaviour towards the environment. A mixed-methods approach was used to collect data. A questionnaire was administered to 60 high school students aged between 16 and 18 immediately after the ESD training. In-depth interviews were then conducted with 44 respondents who completed the questionnaire. The results of the study suggest that formal education, class activities and extracurricular activities can contribute to reshaping students' attitudes and behaviour towards the environment, reflecting not only academic but also personal and social growth. The findings reveal that there are multiple effective ways to embed ESD in a high school curriculum. The study also provides a pedagogical framework for teachers aiming to integrate ESD into their curriculum. While the research involved a limited sample, it could serve as a background for future studies to investigate a larger population.