For rural Grade 7 students in Leyte, Philippines, the move into secondary mathematics means navigating not just harder content, but overcrowded classrooms, multi-hour commutes, and homes with no books or internet. Yet this study found that challenge itself is not the enemy, the real risk is challenge under exhaustion. This study explored the KS2-to-KS3 mathematics transition experiences of 15 purposively selected Grade 7 students through in-depth semi-structured interviews, analyzed using reflexive thematic analysis within three theoretical frameworks. Analysis revealed five themes: the contradictory nature of challenge as both motivator and stressor, compound ecological barriers, prior knowledge gaps in fractions and pre-algebra, teacher responsiveness and peer scaffolding as critical protective factors, and dynamic affective patterns of confidence and anxiety. Critically, all 15 students identified their teacher, not technology, not textbooks, as their primary lifeline. These findings informed the "Bridging Pathways" program, a low-cost, four-component intervention requiring no digital infrastructure, designed for immediate adoption in under-resourced rural schools. This study advances equity-focused mathematics education by demonstrating that teacher development, not infrastructure investment, is the most accessible lever for rural transition support in the Philippines.