Martyn Lloyd-Jones:
We all agree that we should examine ourselves, but we also agree that introspection and morbidity are bad.
But what is the difference between examining ourselves and becoming introspective?
I suggest that we cross the line from self-examination to introspection when, in a sense, we do nothing but examine ourselves, and when such self-examination becomes the main and chief end in our life.
We are meant to examine ourselves periodically, but if we are always doing it, always, as it were, putting our soul on a plate and dissecting it, that is introspection. And if we are always talking to people about ourselves and our problems and troubles, and if we are forever going to them with that frown upon our face and saying: I am in great difficulty—it probably means that we are all the time centred upon ourselves. That is introspection, and that in turns leads to the condition known as morbidity.
D. Martyn Lloyd-Jones, Spiritual Depression, p. 17.