It’s important to start exercising as soon as possible, preferably before or during the course of adjuvant treatment. The sooner you start, the less likely you are to get stuck in the vicious cycle of feeling fatigued, not exercising, feeling more fatigued and even less willing to exercise, and so on. Once you start, you will probably find yourself eager and motivated to continue. Studies found that breast cancer survivors who were instructed to exercise were very motivated to do so and were able to stick with the program.