Mental and physical strength are connected. The mental and physical world are connected. Every intelligent being is always carried in a physical carrier. The interaction between the mental processes inside the intelligent being and the external physical world determines the effectiveness of that intelligent being. Each surviving living entity is a warrior, by definition.
Life equals battle.
Life, in order to at least survive, must be capable of offensive action. Limiting yourself to defense-only equals stagnation. You yourself are the only one deciding about your own actions and your own thoughts. The world is not in control of you, you are in control of the world. Sometimes, the way forward is to free yourself of harmful memes rather than to acquire new memes.