From my experience, most witnesses are asking because they care for "your spiritual health". And I say that in quotes because to them, spiritual health is all about the things you do, like meetings and field service. If you do those things they think, then automatically you will be healthy, which isn't true.
Then there are some witnesses, usually elders who ask to be noisy or think they can fix you. You're hours are low or you've missed meetings. Again pointing back to what you do in those activities means good spiritual health. They are only victims of what they have been taught.
If you look in the Bible, it isn't like that at all.