Ganesh-
Your most valued accomplishment does not have to be a professional one. Remember that the committee is trying to get to know you in these essays, who you are, what makes you tick. Revealing what gives you satisfaction is a great way to provide this insight. I generally advise my clients to reach for your best story, one that will "stick to the ribs" and be remembered. Sometimes professional achievements start to sound very run of the mill, sometimes they can be extraordinary. The key is to be passionate and reveal enough of yourself to stand out amongst other applicants with similar backgrounds. Having said that, considering that this may be one of your only opportunities given the questions to chat about your career, you may indeed want to at least consider a substantial achievement from work to package for the committee. Overall, your application should demonstrate leadership, innovation, maturity and some level of teamwork skills as a baseline. If you can find ways to demonstrate these attributes elsewhere in the application, that's fine, but if it's easier to work these skills into this question, you should. Hope this helps.
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Bryant Michaels
Admissions Consultant