Cancer-related fatigue is serious and complex, as well as one of the most common symptoms experienced by patients with colorectal cancer, with the potential to compromise quality of life, activities of daily living, and ultimately survival. There is a lack of consensus about the definition of cancer-related fatigue; however, definitions have been put forward by the European Association for Palliative Care (EAPC) and the National Comprehensive Cancer Network (NCCN). Numerous cancer- and treatment-related factors can contribute to fatigue, including disease progression, comorbidities, medical complications such as anemia, side effects of other medications, and a number of physical and psychologic factors. This underlines the importance of tackling factors that may contribute to fatigue before reducing the dose of treatment. NCCN guidelines and the EAPC have proposed approaches to managing fatigue in cancer patients; however, relatively few therapeutic agents have been demonstrated to reduce fatigue in randomized controlled trials. It is recognized that physical activity produces many beneficial physiologic modifications to markers of physical performance that can help to counteract various causes of fatigue. In appropriately managed and monitored patients with colorectal cancer, emerging evidence indicates that exercise programs may have a favorable influence on cancer-related fatigue, quality of life, and clinical outcomes, and therefore may help patients tolerate chemotherapy. This review assesses fatigue in patients with colorectal cancer and proposes updates to a treatment algorithm that may help clinicians manage this common problem.