Street version: Life is 10% what happens to you and 90% how you respond to it.
PIGG version: Life is 12.865% a causation factor involving random events occurring in an existential fulcrum and intersected by continual rises and falls of attitudinal energy and 83.125% how ones presynaptic neurons react to a chemical called a neurotransmitter that binds to receptors located in the postsynaptic cell, usually embedded in the plasma membrane. Binding of the neurotransmitter to a receptor can affect the postsynaptic cell in a wide variety of ways. The remaining percent? We have no fucking idea.