Objectives. To (1) examine whether reducing discrepancies between goal importance and goal attainability is an adaptive predictor of well-being, (2) investigate intrusion, awareness, optimism, and pessimism as determinants of reducing discrepancies between goal importance and goal attainability, and (3) explore how goal progress is involved in reducing discrepancies between goal importance and goal attainability during two major periods after a colorectal cancer diagnosis.Design. Prospective design.Methods. Newly diagnosed colorectal cancer patients (n = 120) were interviewed three times: within a month, 7 months (treatment period), and 18 months (followup period) post-diagnosis. Data were analysed using multiple regressions.Results. Results showed that (1) reducing discrepancies enhances well-being, (2) optimism and pessimism are predictors of reducing discrepancies during the treatment period but not during the follow-up period, while intrusion and awareness do not predict reducing discrepancies in either period, and (3) goal progress is a predictor of reducing discrepancies during the follow-up period, but no evidence for a moderating or mediating role of goal progress in the relation between psychological characteristics and reducing discrepancies was found.Conclusions. Reducing discrepancies between goal importance and goal attainability could benefit colorectal cancer patients' well-being. Optimism, pessimism, and goal progress appear to influence cancer patients' ability to reduce discrepancies. Providing assistance in improving goal progress to those who are less optimistic and highly pessimistic may be a suitable training for cancer patients to prevent deterioration in wellbeing.