Young adult cancer survivors have a number of increased health and psychosocial risks. To minimize these risks, they must address any modifiable risk factors, for example increase their physical activity (PA) and reduce stress. Unfortunately, more than half of young survivors remain sedentary, and few participate in a structured form of relaxation. This study evaluated the feasibility, acceptability, and effects of a theory-based PA and meditation intervention for young survivors. Young adult cancer survivors (age 18-39 years) were randomized to receive the 12-week "RElaxation aNd Exercise for Wellness" (RENEW) intervention right away (intervention group) or after a 12-week wait (control group). Participants were assessed at baseline, 12 weeks, and 24 weeks. Thirty-five survivors were enrolled and randomized. Results indicate that 89% of intervention calls were delivered, and most participants felt that intervention goals and the number and duration of intervention calls were appropriate. Satisfaction ratings indicate that the intervention was acceptable, and 100% of participants would recommend it to others. Comparison of the intervention and control groups at the 12-week assessment (i.e., before controls received the intervention) revealed that the intervention group was performing more minutes of at least moderate intensity PA/week (p = 0.002; M = 113.8, SE = 23.5 vs. M = -8.7, SE = 27.1) and outperformed controls on a test of cardiovascular fitness (p = 0.008; M = -1.76, SE = 0.41 vs. M = -0.03, SE = 0.45). When data from the intervention and control groups were pooled, pre- to post-intervention analyses indicated a trend toward improved mood. This theory-based intervention for young adult cancer survivors was feasible and acceptable, and may have helped survivors increase PA, improve fitness, and enhance mood.