Nobody cares how I am doing. They are asking out of politeness so I give them the sketchiest outline before I turn the spotlight on them. If they are genuinely interested they have the option of asking more questions. I keep an open body language. If they show no further interest, I don't hold it against them or judge them. I don’t show much interest in others' lives either. Maybe we can have a deep and meaningful about a specific topic. But generally asking about each other is more about social nicety than genuine interest, in my humble opinion. I do respect contrary opinions, though.