:::OshnSoul:::

My honest answer to this question which I have been asked is "not having enough to do. Although my workload can get overwhelming, I'd much prefer it over not having enough workload. I always make sure I find something to do that will benefit the company, such as lending a hand to other co-workers who may need help with their tasks, I love learning new things."
-Even though it doesn't sound like a weakness, it has worked as far as impressing the interviewer.