Past research has indicated the vital role of affective factors in mathematics learning. This action research study aimed to develop and evaluate the effectiveness of an action plan, which was implemented to foster students' positive affective entry characteristics towards mathematics specifically by fixing the deficiencies in prior learning and promoting the allocation of time to study. Thirteen students attending a secondary school participated in the study over a 12-week period. We collected both quantitative and qualitative data through the Affective Entry Characteristics Scale for Mathematics, the Attitude Observation Form towards Mathematics, the research diary, and indirect observation of use traces on student assignments. First of all, the analysis of these data sources confirmed that there was a substantial improvement in the students' affective entry characteristics, indicating the effectiveness of our implementation. On the other hand, the qualitative data analysis of the diary and student assignments revealed that this effect was not long-lasting for students who lived in a disadvantaged family/home environment. In other words, remedying the deficiencies in prior learning and promoting the allocation of time to study alone were not sufficient for these students. As a result, we came to the conclusion in the study that non-modifiable variables (such as family home environment) are as important as or even more important than modifiable ones in the development of positive affective entry characteristics towards mathematics.