Read the following excerpt from a fictional narrative:
After years of struggling to make ends meet, Liam finally received a job offer that could change his life. He was ecstatic, but doubts lingered—was he truly qualified? As he prepared for the big day, memories of past failures crept into his mind, casting a shadow over his excitement. The morning of the interview, he hesitated at the front door, his heart racing. Would he step through and embrace the challenge, or retreat into the familiarity of his old life?
In this excerpt, what is the main plot structure that conveys Liam's internal conflict?