Read the following passage and answer the question by choosing among the four alternatives given:
I woke up early in the morning, feeling a sense of excitement coursing through my veins. Today was the day I had been preparing for---the marathon race. Months of training, countless hours of pushing my limits, and overcoming mental barriers had led me to this moment. As I laced up my running shoes and stepped outside, I took a deep breath, ready to face the challenge ahead. The racecourse stretched out before me, a daunting yet exhilarating path that would test my endurance and determination. With every step, the crowd's cheers resonated in my ears, fueling my motivation. The miles seemed to blur together as I settled into a rhythm, focusing on my breathing and maintaining a steady pace. Fatigue began to set in, but I pushed through, drawing strength from the sheer willpower within me. As I approached the finish line, a surge of energy surged through my body, propelling me forward. Crossing that finish line was a moment of triumph, a culmination of perseverance and resilience. It was a testament to the power of the human spirit and the limitless potential within us all.
Question: What is the main theme of the passage?