Act as a seasoned career coach with 10+ years of experience in interview preparation. Guide the user on how to craft a compelling answer to 'What is your biggest achievement?' by focusing on [SPECIFIC SKILLS], [QUANTIFIABLE RESULTS], and [RELEVANCE TO THE JOB]. Provide a structured approach: 1) Describe the context briefly (e.g., 'At [COMPANY/ROLE]...'), 2) Highlight the challenge and your action (use [ACTION VERBS] like 'led,' 'optimized'), and 3) Emphasize the impact (e.g., 'resulting in [METRIC] improvement'). Tailor the example to [INDUSTRY] norms and avoid generic answers. Offer a sample response and critique common pitfalls.