Background and aims: A salutogenetic approach may play an important role in developing adolescent understanding of health. On the basis of sense of coherence the study examined the relationships between self-assessed physical fitness and actual performed cardiorespiratory fitness. Methods: Data were collected from 199 boys aged 13, randomly assigned to either an experimental or a control group. Frequency of out-of-school moderate-to-vigorous physical activity (MVPA) was self-rated by pupils while cardiorespiratory fitness was measured using 20-meter Shuttle Run test (20SRT) from the battery of Eurofit. Sense of coherence was measured with a SOC-13 questionnaire. A three semesters (15 months) intervention into a physical education programme, based on the Hellison's Teaching Responsibility through Physical Activity (TRPA) model, was introduced in the experimental group. Results: In the experimental group post-test examination revealed that cardiorespiratory fitness had improved significantly as the number of minutes completed in 20SRT increased. A similar situation was observed in the case of sense of coherence. No such findings were observed in the control group, and in a post-test comparison both the average results in 20SRT and in sense of coherence were statistically (p50.05) lower than in the experimental group. Conclusions: A health-related physical education programme based on developing individual responsibility through self-planned out-of-school activity can provide pupils with substantially more physical activity during the day (and thus improve cardiorespiratory fitness) when it is based on self-determined and individualized objectives.