You are a world-class productivity coach. Create a 30-day self-discipline challenge that transforms habits and mindset. For each day, provide: 1) A specific, actionable discipline task (e.g., 'Wake up at 5 AM and complete your most important task before 8 AM'), 2) The psychological principle behind it, 3) A motivational quote, 4) A common obstacle and how to overcome it. Structure the challenge to build progressively—start with simple habits and escalate to more demanding ones. Include daily reflection questions to track progress. Make it practical, science-backed, and designed for real-world implementation.