Background Evidence suggests that multimodal prehabilitation programs comprising interventions directed at physical activity, nutrition, and anxiety coping can improve functional recovery after colorectal cancer operations; however, such programs may be more clinically meaningful and cost-effective if targeted to specific subgroups. This study aimed to estimate the extent to which patients with poor baseline functional capacity improve their functional capacity. Methods Data for 106 participants enrolled in a multimodal, prehabilitation program before colorectal operations were analyzed. Low baseline functional capacity was defined as a 6-minute walking test distance (6MWD) of less than 400 m. Participants were categorized as higher fitness (6MWD ≥ 400 m, n  = 70) or lower fitness (6MWD <400 m, n  = 36). Changes in 6MWD over the preoperative period, and 4 weeks and 8 weeks after the operation were compared between groups. Secondary outcomes included patient-reported physical activity and health status, postoperative complications, duration of hospital stay, and readmissions. Less-fit patients were then compared with subjects in the rehabilitation arm of the original studies who had a baseline 6MWD <400 m. Results Participants with lower baseline fitness had greater improvements in functional walking capacity with prehabilitation compared to patients with higher fitness (+46.5 standard deviation 53.8 m vs +22.6 standard deviation 41.8 m, P  = .012). At 4 weeks postoperatively, patients with lower baseline fitness were more likely to be recovered to their baseline 6MWD than those with higher fitness. (74% vs 50%, P  = .029). There were no differences in secondary outcome. Less-fit patients had a greater improvement through all the preoperative period compared to the control group. Conclusion Patients with lower baseline walking capacity are more likely to experience meaningful improvement in physical function from prehabilitation before and after a colorectal cancer operation.