In order to get a request, your manuscript’s first page must snag the agent immediately. One big thing that divides requested manuscripts from rejected ones is:
Don’t start with thoughts: start with activity.
Manuscripts lose the reader’s attention when they start in characters’ heads. Frustration, anger, and apathy are weak beginnings. The protagonist must be frustrated in order to create conflict, but the first page needs to show that. Rather than the protagonist narrating, the protagonist should do something and let us observe their feelings by their actions. (Consequently, the activity must revolve around their current goals and struggles.)
Be careful not to start your protagonist on their first plot point, the point of no return. Maggie Steifvater’s book THE RAVEN BOYS does not begin with Blue returning Gansey’s journal. It begins with Blue waiting in a cemetery for next year’s dead to appear. That activity starts Blue’s story.
It is also an interesting activity. It piques my curiosity.
Starting with internal monologue is a sign that the external activity is too boring. Start the story with different action or make whatever is happening worth paying attention to.
Note: memories, despite happening in the character’s head, can be okay if they include interesting activity. Use sensory words and active verbs. But keep them short and only use them as an adjunct to what’s happening in the scene.