This paper studied the effects of prescribed brisk walking in lowering heart rates among chosen fourth-year students at X National High School in Region X, using a quasi-experimental design that looked at the study's outcomes after an intervention program was implemented. This study used a pre-test and post-test design in which students were given an intervention program and were separated into two groups: 15-minute exercise and 10-minute exercise. The pre- and post-test findings of the two groups were compared to determine the considerable increase in cardiovascular fitness and reduction in heart rates among the study participants.The findings revealed that more female student-respondents had superior heart rate performance than male student-respondents, owing to other characteristics that may have considerably influenced the female student-respondents' heart rate performance. It's also worth noting that the heart rates of the student-respondents differ before and after they've completed the specified 15-minute and 10- minute brisk walking exercises as part of the intervention program. As a result, the 15-minute and 10-minute durations of brisk walking exercise effectively increased the cardiovascular endurance level of the studentrespondents in this study, notably in terms of lowering their heart rates.