The concept of subjective vitality refers to the state of feeling alive and alert–to having energy available to the self. Vitality is considered an aspect of eudaimonic well-being (Ryan & Deci, 2001), as being vital and energetic is part of what it means to be fully functioning and psychologically well.
Ryan and Frederick (1997) developed a scale of subjective vitality that has two versions. One version is considered an individual difference. In other words, it is an ongoing characteristics of individuals which has been found to relate positively to self-actualization and self-esteem and to relate negatively to depression and anxiety. The other version of the scale assesses the state of subjective vitality rather than its enduring aspect.
At the state level, vitality has been found to relate negatively to physical pain and positively to the amount of autonomy support in a particular situation (e.g., Nix, Ryan, Manly, & Deci, 1999). In short, because the concept of psychological well-being is addressed at both the individual difference level and the state level, the two levels of assessing subjective vitality tie into the two level of well being.
The original scale had 7 items and was validated at both levels by Ryan and Frederick (1997). Subsequent work by Bostic, Rubio, and Hood (2000) using confirmatory factor analyses indicated that a 6-item version worked even better than the 7-item version.