Background - To systematically review the effects of interventions to improve exercise behaviour in sedentary people living with and beyond cancer. Methods - Only randomised controlled trials (RCTs) that compared an exercise intervention to a usual care comparison in sedentary people with a homogeneous primary cancer diagnosis, over the age of 18 years were eligible. The following electronic databases were searched: Cochrane Central Register of Controlled Trials MEDLINE; EMBASE; AMED; CINAHL; PsycINFO; SportDiscus; PEDro from inception to August 2012. Results - Fourteen trials were included in this review, involving a total of 648 participants. Just six trials incorporated prescriptions that would meet current recommendations for aerobic exercise. However, none of the trials included in this review reported intervention adherence of 75% or more for a set prescription that would meet current aerobic exercise guidelines. Despite uncertainty around adherence in many of the included trials, the interventions caused improvements in aerobic exercise tolerance at 8-12 weeks (SMD=0.73, 95% CI=0.51-0.95) in intervention participants compared with controls. At 6 months, aerobic exercise tolerance is also improved (SMD=0.70, 95% CI=0.45-0.94), although four of the five trials had a high risk of bias; hence, caution is warranted in its interpretation. Conclusion - Expecting the majority of sedentary survivors to achieve the current exercise guidelines is likely to be unrealistic. As with all well-designed exercise programmes, prescriptions should be designed around individual capabilities and frequency, duration and intensity or sets, repetitions, intensity of resistance training should be generated on this basis.