I wasn't too keen to hear this from a candidate recently, especially when there is so much information available for interviewees. Take for example our interview tip guide found http://people2people.com.au/interview/preparing-for-the-interview/ .
There are ample interview examples to ensure you are as prepared as possible to handle those curly questions. I'd recommend just having a few work examples which highlight a lot of your different strengths. That way, you can keep bringing the interviewer back to the same examples. This cam make the interview a lot less complicated and easier for both of you.
Don't be worried if these strengths don't sound too unique, the fact you're aware they are important for you to do your job well, is what matters. Being able to get through the interviewer’s questions with solid examples of your proven strengths, means there is more time for you to start asking some of the questions you want answered and thereby, have a better feel of the role and the team. So ‘winging it’ doesn't need to happen anymore, instead get thinking and preparing and you might even start enjoying those annoying interviews!