* Bilbo's initial reluctance: Bilbo was deeply uncomfortable with the idea of leaving his comfortable hobbit-hole and venturing into the unknown. He even tries to back out several times, but Gandalf encourages him and plays on his desire for adventure.
* The "second thoughts" at the party: After the company assembles, Bilbo gets cold feet again and contemplates leaving. He realizes that he is completely unprepared for such a journey, and he's afraid of the dangers that await.
* Gandalf's encouragement: Gandalf doesn't force Bilbo to stay. He simply emphasizes the importance of the quest and the potential for Bilbo to discover things about himself. He reminds Bilbo that he already agreed to go and that backing out now would be cowardly.
* Bilbo's decision to stay: Ultimately, Bilbo decides to stay not because Gandalf forced him, but because he recognizes the value of the adventure and the opportunity for personal growth. He's still afraid, but he chooses to face his fears and be a part of something bigger than himself.
In essence, Gandalf guides and encourages Bilbo, but it's ultimately Bilbo's own decision to stay. The journey is about self-discovery, and Gandalf's role is to help Bilbo find his own courage and embrace the adventure.