NEVER. NEVER EVER. NEVER. Say anything cheesy like you don't have any weaknesses, you're great weakness is actually your greatest strength because..., or that you too hard of a worker. Managers have heard that a billion times and it takes every effort not to eye roll and end the interview right there. Trick is to frame weaknesses as a learning opportunity, "Like I use to have trouble performing INSERT TASK HERE, so I took a class so I could become more proficient and now I'm doing much better!" This question is to determine whether or not you can be honest about yourself, whether or not you're full of it, and if you can learn from your mistakes and be humble about it. Doesn't really matter what you say as long as you frame your answer as a lesson learned.