An exerciser that is anxious and not confident about their ability to complete an exercise is experiencing a low amount of:

The exerciser’s feelings of anxiety and lack of confidence regarding their ability to complete an exercise are directly tied to the concept of self-efficacy. Self-efficacy refers to an individual's belief in their own capabilities to execute behaviors necessary to produce specific performance attainments. When someone feels anxious and unconfident, it suggests that they do not believe they can successfully perform the exercise, indicating a low level of self-efficacy.

In contrast to self-efficacy, self-awareness is more about understanding one's emotions, strengths, weaknesses, and triggers. It does not specifically address the confidence in performing tasks or exercises. Self-absorption and self-centeredness generally refer to a focus on oneself in a way that detracts from recognizing others or the broader context. These concepts are not relevant to the concern of feeling anxious or lacking confidence in exercise performance. Therefore, the correct choice clearly links the emotional state of anxiety and lack of confidence to self-efficacy, which is crucial for motivation and behavioral change in exercise scenarios.