My best friend of almost 10 years is an INFJ. She doesn't like to lead, but recently became a manager and moved up the work ladder. They had offered it to her before and she declined, but this time I think they persuaded her by showing her how she was helping out the store. It seems to me that when she is either very happy and caring, she will lead, and also when she is furious, she will take the lead -out of impatience. I think whenever a strong emotion is involved, then they are inclined to be a get-it-done leader. Very thorough and fast.