This fear appears in almost everyone before the first sessions, and behind it there is usually a belief: that therapy is an exam you must arrive at with the material prepared.
What concretely helps:
Start with what is on the surface. It does not have to be the most important event. “This week was hard at work” generally leads exactly where it needs to, just by another road.
Describe the sensation, not the conclusion. If you do not know what you feel, describe what is happening in your body — a knot in the chest, tight shoulders, a hollow stomach. It is as valid a starting point as a story.
Bring the silence into the conversation. “I find it hard to talk about this” or “I don't know why this is hard right now” are sentences with content, not evasions.
You do not have to fill the space. Silence in a session is not wasted time. Sometimes it is precisely where something appears.
If the block persists past a few sessions, say so out loud — it may mean the pace is too fast, that not enough safety has been built yet, or that the method does not fit. All three are things a therapist can adjust, but only if they know.
A good therapist does not expect you to arrive with the order already made. If you had it, you probably would not need them.