What kind of life events or situations are "fight or flight" moments? What are some psychological and physiological effects?

Answer 1

We experience a fight or flight response when we feel threatened. Often a tragedy such as the death or serious illness of a loved one or a broken marriage/love affair will trigger such a response.

http://changingminds.org/explanations/brain/fight_flight.htm

http://en.wikipedia.org/wiki/Fight-or-flight_response