Students with awareness and control of their own thinking can learn more and perform better than students who are not metacognitive. Metacognitive regulation is how you control your thinking in order to learn. It includes the skill of evaluation, which is the ability to appraise your approaches to learning and then modify future plans based on those appraisals. We asked when, why, and how upper-division biology students evaluated their approaches to learning. We used self-evaluation assignments to identify students with potentially high metacognition and conducted semi-structured interviews to collect rich qualitative data from them. Through content analysis, we found that students evaluated their approaches to learning when their courses presented novel challenges. Most students evaluated in response to an unsatisfactory grade. While evaluating study strategies, many students considered performance and learning simultaneously. We gained insights on the barriers students face when they try to change their approaches to learning based on their evaluations. A few students continued to use ineffective study strategies even though they were aware of the ineffectiveness of those strategies. A desire to avoid feeling uncomfortable was the primary reason they avoided strategies that they knew were more effective. We examined the behavioral change literature to help interpret these findings.