"I know, I know, I know you are right, thanks for your concern"....that makes me feel like a punk...I think to myself: "fight back p*ssy!"
I would caution against saying "I know you are right" as that takes away from any personal ideas or beliefs of your own. It also supports their usual opinion you are too weak or lazy to do what you agree is the proper thing to do (ie: as you are told at the meetings).
Although you may initially consider it weak to not argue an opposing point of view, upon consideration you may realize there is little if anything to be gained by doing so. Why waste your time attempting to reason with someone who comes equipped with a pre-conceived agenda and who really is not interested in hearing your opinions, ideas or excuses.
As an adult, ultimately you are responsible to yourself for what you believe or do not believe so you do not need to provide an explanation or excuse to this JW elder or any JW.