The response rate was 28% (106 of 383 patients). Descriptive analyses indicated that 42%, 38%, and 41% of participants, respectively, met national exercise prescription guidelines prior to diagnosis, during treatment, and after the completion of adjuvant therapy. Repeated measures analyses indicated no significant changes in the majority of exercise behavior outcomes over the cancer trajectory. However, exploratory analyses indicated that males and younger participants may be at the greatest risk of reducing exercise levels after a brain tumor diagnosis. These analyses remained unchanged after controlling for relevant demographic and medical covariates.