 Have you hit the gym yet today? Chances are it's tough enough to do regularly if you're healthy. If you've got cancer, that seems especially hard. But for cancer patients, exercise can be a kind of therapy. Working out can boost mood and actually help patients feel less tired and better able to cope with the side effects of treatment. Most studies, though, have only looked at exercise for individual cancers, making it impossible to tell which patients and which types of cancers are most likely to benefit. Might exercise programs work for breast cancer patients, but do nothing for people with lung cancer? Researchers at the University of Northern Colorado decided to find out. They enrolled about 700 patients with a wide variety of tumors in a three-month exercise study, all complained of side effects of their cancer treatment. The scientists took the participants' baseline measurements, including heart rate, blood pressure and lung function, and also gave patients a treadmill test for aerobic capacity and a questionnaire to gauge how disruptive fatigue was to their everyday lives. Each patient then received an exercise program tailored just for them. About 300 patients followed through and worked out with a specialist for an hour three times a week. The sessions varied, but included a warm-up, something to get the blood pumping, such as walking or cycling, as well as resistance training and flexibility and balance exercises. At the end of three months, the scientists measured the participant's stats again. For almost all types of cancer, the numbers had moved in the right direction. Heart rate and blood pressure were lower. Aerobic capacity had gone up. Fatigue had gone down. The only measure that remained stubbornly the same was pulmonary function. Not all of the shifts were statistically significant. Participants with prostate or glandular and epithelial cancer only saw significant improvements in aerobic capacity. Just heart rate and fatigue fell significantly in colon cancer patients, whereas all measures improved for breast cancer patients. But overall, the results didn't differ based on cancer type. The breast cancer group was more than four times the size of the next largest, so small sample sizes prevented many of the changes in other cancer types from being significant. The findings suggest that doctors should prescribe exercise regimens for cancer patients based on individual needs rather than paying attention to cancer type. Future work, though, may reveal whether patients with certain cancers benefit more from working out in terms of muscle strength, flexibility, and quality of life.