Generate a full detail guide on the art of saying 'no.' The guide's tone should be empowering and practical. It must include sections on: 1. Why Saying 'No' is a Crucial Skill for Preventing Burnout. 2. How to Overcome the Guilt Associated with Saying 'No.' 3. A List of Polite and Firm Scripts to Use in Different Scenarios. 4. How to Offer an Alternative Instead of a Hard 'No' When Appropriate. Please include a supportive disclaimer.