More or Less Energy With Age? A Motivational Life-Span Perspective on Subjective Energy, Exhaustion, and Opportunity Costs

Two studies investigated subjective conceptualizations of energy for goal pursuit across adulthood. Study 1 (N = 276, 20-92 years of age) explored age-related differences in the (a) endorsement of a limited versus nonlimited account of energy for goal pursuit, (b) amount of energy available for physically, mentally, socially, and emotionally demanding activities, and (c) extent to which spending energy on a demanding activity inhibits or facilitates energy expenditure for subsequent activities, both within and across functional domains. Study 2 (N = 147, 18-86 years of age) experimentally induced energy loss through a 20-min physical exercise and examined age-related differences in the increase of subjective exhaustion and opportunity costs as a motivational cue for goal disengagement. With increasing age, adults more strongly endorsed a nonlimited account of energy and perceived having more energy available for personally relevant social activities. However, older adults also reported higher negative cross-domain energy spillover after physical exertion. Multilevel growth curve models further revealed that, compared with younger adults, older adults reported a steeper initial increase in exhaustion and opportunity costs during physical exercise, but converged with the younger age groups again at the close of the exercise session. The discussion centers around the importance of selectivity in older adulthood and motivational accounts of effort and exhaustion.