He had been living under a black cloud of depression.
Demonstrating assertiveness means there's no question where you stand, no matter the topic. Cognitively, to be assertive implies a lack of anxious thoughts in light of stress. Behaviorally, assertiveness is all about asking for what you want in a manner that respects others.
Peter Drucker famously stated that when "management is doing things right, leadership is doing the right things." Great leaders possess dazzling social intelligence, a zest for change, and above all, a vision that allows them to set their sights on the things that truly merit attention.