Psychological flexibility and peer support promote lifestyle changes
Psychological Flexibility Supports Well‑Being
In her dissertation, Mari Petäjä examined psychological flexibility and its association with well‑being in a lifestyle change intervention delivered within Finnish healthcare services. The study involved 177 primary healthcare clients who took part in group sessions, ACT‑based online exercises and support phone calls from trained peer tutors.
Participants’ lifestyle change processes were assessed four times during the two‑year intervention. Increases in psychological flexibility were associated with improved self‑rated health, particularly among participants whose initial self-rated health status was moderate or poor. These participants also reported enhanced depression‑related quality of life, which was similarly linked to increased psychological flexibility. Additionally, individuals with low baseline levels of physical activity increased their activity during the intervention.
According to Petäjä, psychological flexibility refers to the ability to identify personal values and take value-based actions, observe one’s thoughts and emotions with openness, remain present, and approach situations from new perspectives. As self‑rated health is known to predict future functional capacity, the observed connection between changes in psychological flexibility and self‑rated health over the follow‑up period is meaningful.
New Insights into Supporting Long‑Term Change
Earlier research has shown that training psychological flexibility is beneficial across a range of population groups and life situations. This dissertation provides new insight into supporting long‑term lifestyle change, demonstrating that an ACT‑based intervention is effective even when partially delivered online. The most substantial changes occurred during the first year, when peer tutor support was at its most intensive.
“The findings highlight the long‑term benefits of psychological flexibility training in lifestyle change."
"They also indicate that training peers to support individuals undergoing lifestyle changes is a valuable component of public well‑being services,” Petäjä notes.
Support for lifestyle change should include guidance in identifying everyday barriers and navigating challenging periods of time. A sense of being heard and opportunities to share experiences with others can also play an important role. Psychological flexibility training provides individualized tools throughout the change process and can be integrated into existing well‑being services.
Mari Petäjä’s doctoral dissertation in health promotion, “The Psychological Flexibility in Lifestyle Change: Results of a Peer-Tutored Acceptance and Commitment–Based Two-Year Lifestyle Intervention”, will be examined at the University of Jyväskylä in the main building, hall C1, starting at 12:00 on 20 February 2026. The opponent will be Professor Tiina Laatikainen (Itä-Suomen yliopisto) and the custos Professor Sami Kokko (Jyväskylän yliopisto). The public defence will be held in Finnish and can also be followed online.
Publication Details
The dissertation is available in the JYX repository.
Mari Petäjä holds a Master of Health Sciences degree with a major in health education and is a registered nurse. She has worked at Jamk University of Applied Sciences since 2009—first as a Senior Lecturer in health promotion and nursing and, since 2021, as a Senior Lecturer and teacher educator at the School of Professional Teacher Education. During her doctoral studies, she has worked for two years as a doctoral researcher at the Faculty of Sport and Health Sciences, University of Jyväskylä.
Further information:
Mari Petäjä
mari.petaja@jamk.fi, +358400226025
