Remember there are two questions here, strength is your ability to excel in the workforce, list out a few and explain or give examples, without which your strength doesn't impress the interviewer. When it comes to weakness, you are talking about challenges you will have against your strength. DO not talk about threats, for example, I am lazy, I am bored, I am an alcoholic, I am a chain smoker, etc... these create a bad impression. Weakness... example, "I am more time in finishing a project, the question would be why? then say I am into details, I do not like to submit a project with errors, so keep a close watch on the details to add to my project."