Patients with colorectal cancer are offered multi-factual treatment which means long-term treatment followed by severe side effects. Within a phenomenological-hermeneutical frame of reference, the aim of this study was to explore the patients’ perceptions of the challenges they experience during treatment for colonic cancer. Ten patients participated in the study. Data were collected through semi-structured interviews and analysed using the guidelines for meaning interpretation laid out by Kvale and Brinkmann. The analysis led to one dominating theme: endurance, and four subthemes: coping with bodily changes; the reorganization of everyday life; getting support from close relatives; seeing life from a different perspective. The patients struggled to endure both the ongoing treatment and the changes in their everyday lives related to the disease and the unpleasant side effects, such as diarrhea. The findings demonstrate a need for an increased awareness of the impact of diarrhea on patients’ everyday lives during treatment.