"Why do we give up?"
In experiments by Martin Seligman, dogs that were repeatedly shocked with no escape eventually stopped trying to flee, even when the door was opened. This is Learned Helplessness. When we believe we have no control over our suffering, we fall into depression and passivity.
Depression is often a result of ingrained negative thought patterns ("I am a failure," "Nothing will change"). Cognitive Behavioral Therapy (CBT) works by identifying these distorted thoughts and challenging them with reality. By experiencing small successes and reclaiming control, the brain can "unlearn" helplessness. Optimism and resilience can be learned.