The coronavirus pandemic has influenced many lives, particularly older adults'. Although isolation protects from infection, health behaviors like physical activity (PA) are important to reinstate after lockdown. However, fear of Covid‐19 may act as a barrier, for example, by preventing people from going outside. Based on the health action process approach (HAPA), we investigated whether and why older adults' PA changed after lockdown, and whether fear of Covid‐19 moderates the intention–behavior relationship. Participants of this longitudinal study aged 65+ from German‐speaking Europe completed an online questionnaire about their PA, fear of Covid‐19, and HAPA factors in April and May 2020. Data were analyzed using multiple linear regressions. Results showed that moderate to vigorous activity (MVPA) remained stable after lockdown and that self‐efficacy most robustly influenced the intention to be active. PA was not explained by any volitional factor but was strongly related to past PA. Interestingly, the relationship of past and future MVPA was attenuated by fear of Covid‐19, but this finding was not robust when outliers were removed. In conclusion, self‐efficacy is the most important motivator for PA in older adults after an interruption like a lockdown. Strong physical activity habits may facilitate PA after a period of isolation.

Objectives: Physical activity is an important health behaviour especially for older adults. Forming implementation intentions is an effective strategy to implement physical activity in daily life for young and middle-aged adults.However, evidence for older adults is inconclusive. This study explored the thoughts of older adults about implementation intentions and potential barriers and facilitators while formulating them. Methods: Three samples of older adults from the United Kingdom (n = 8), Germany (n = 9) and Switzerland (n = 17) were prompted to think aloud while formulating implementation intentions to be more physically active. After the task, semi-structured interviews were conducted. Data were analysed thematically. Results: Participants expressed pre-established thoughts about implementation intentions (e.g. they feel too restrictive). During the formulation of implementation intentions, several barriers to creating them were reported (e.g. problems with finding cues due to absence of recurring daily routines), but participants also mentioned that forming implementation intentions acted as a facilitator for physical activity (e.g. cues as useful reminders to be active, task itself triggering self-reflection about physical activity). After the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.