Specific psychological constructs and comprehensive models or theories have been designed to account for individual differences in the way people abstain from risk behaviors, adopt health behaviors, and succeed or fail in self-regulatory attempts. The present article traces the development of recent health behavior theories and relates them to research in the fields of motivation and self-regulation. Special emphasis is placed on optimism, both as a state and as a trait construct within self-regulatory processes. It is argued that optimistic self-beliefs may be phase-specific. For example, some individuals may have high confidence in their ability to set ambitious goals, whereas others may have high confidence in their ability to recover from setbacks. Moreover, a distinction is made between goal attainment processes and threat appraisal processes. Thus, emotions and behavior may differ when striving for superior health goals as opposed to coping with health threats. The present considerations are put forward to further elaborate the author's Health Action Process Approach (HAPA).