"The Assertiveness Workbook: How to Express Your Ideas and Stand Up for Yourself at Work and in Relationships" by Randy J. Paterson: This is a highly practical, step-by-step guide filled with exercises and strategies to help individuals develop and practice assertive communication skills in various life contexts, from professional settings to personal relationships.

Man's Search for Meaning" by Viktor Frankl: A foundational work on resilience. Frankl's account of surviving concentration camps profoundly explores the human need for meaning, purpose, and the indomitable spirit. It teaches that even in the most horrific circumstances, we have the freedom to choose our attitude and find meaning, a core tenet of spiritual resilience.

Adam Grant's Books (e.g., "Give and Take," "Originals," "Think Again"): While not solely focused on spirituality or explicit resilience, Adam Grant's work consistently emphasizes character, empathy, and intellectual humility – qualities that underpin ethical leadership and the ability to adapt and learn from challenges. "Give and Take" promotes a mindset of contribution, which can be seen as a spiritual practice in leadership, while "Originals" and "Think Again" foster mental agility and resilience in the face of new ideas and changing circumstances.