The Tipping Point as it relates to self-perception.
For example: the more often I have negative thoughts about myself, the more likely it that all my thoughts about myself will turn negative.
Girls in high school are involved in many things. Where does that go?
Consider the Thomas Pinchon quote (from The Crying of Lot 49) about women captive in the tower. If men struggle to find healthy ways to prove themselves, what do modern women struggle with that they never used to? What dreams get squished by life? What momentum gets diverted by the responsibilities of life?
Moving from child to adolescence to adult always results in a loss of momentum. If the move to the next stage involves a change in direction, the result is a loss of momentum.
Any action creates momentum. In the novel, The Lord of the Flies, one of main characters, Ralph blows into a conch shell and the sound draws the rest of the stranded boys to him. This act causes him to be the leader and demands other action by him: he is expected to address the gathered boys. Which, in turn, precipitates other action.