I got that from counseling when I was going through my 2 year brain fart. It's from the book "A Womans Book of Life" by Joan Borysenko. I'll give a quote:
In early and middle adulthood the process of adolescing, or growing up, coexists with the process of senescing, or growing down, periods when our life structures go in to decline. The life structure is defined as a boundary between ourselves and the external world that functions as framework for occupational and family relationships. It is composed of our hopes and dreams, values and talents. How will we fit into the world? What is important to us? What will make us happy?
The period that spans the late teens to mid forties is one of building the life structure for our adulthood. The early thirties are what he calls a "structure-changing or transitional period that terminates the existing life structure and creates the possibility for a new one". .....
The major task involved in the age thirty transition, which Levinson found to span the years between 28 and 32, is the exploration of new possibilities and the finishing up of old business that may be getting in the way of a woman's continued growth.
Inherent in reevaluating what Levinson calls our "necessarily flawed" early life structures, are nagging questions about how to combine work and family, whether to combine work and family, and whether early marriage partnerships are working out. These questions may be further confounded by the stress of infertility. Many women in their 30's want to be mothers, but either can't conceive or have trouble carrying the pregnancy to term. Will they persevere in trying to conceive or alter their life plan? Central to a woman's age thirty transition is the question "what do I really want?"
etc....
Having gone through mine, I would relate it to a mid life crisis. Your confused about who you are, what you want, why you made previous choices that you did..what you really believe etc... For me it was "Who am I really? Who do I want to be? What do I really want from my life?"