CASTLER is a seven-step personal development framework designed for individuals who struggle to initiate or sustain goals due to low knowledge, lack of structure, or motivational burnout. The sequence — Collect, Analyse, Segregate, Test, Layout, Execute, Repeat — guides a person from absolute zero knowledge to consistent, personalised execution without relying on willpower or fixed schedules. Unlike existing frameworks such as SMART Goals, Atomic Habits, or the PDCA Cycle, CASTLER begins before knowledge exists and builds personalisation directly into the process through its testing and layout phases. Its built-in recovery system allows re-entry at the Test or Layout phase after any disruption, ensuring progress is never fully lost. Applicable across habit building, fitness, language learning, skill acquisition, finance, career development, content creation and more, CASTLER functions as a structured, adaptable and individually driven engine for sustainable self-development.