Generate a full detail guide on using laughter and humor to improve mental happiness. The guide's tone should be lighthearted and fun. It must include sections on: 1. The science behind why laughing makes us feel good. 2. How to actively look for humor in everyday situations. 3. Tips for creating a 'humor diet' (e.g., following funny accounts, watching stand-up comedy). 4. The benefits of laughing at oneself in a gentle way. Please include a supportive disclaimer.