Starting next week and honestly a bit nervous

My first session is scheduled for Monday. I am dealing with a non healing wound and my doctor recommended this as part of treatment. The medical reasoning makes sense but I am still nervous.
Mainly about the enclosed space aspect. I do not love small spaces and the idea of being in a chamber for an hour is making me anxious. The clinic said I can bring headphones and they can stop anytime if I need out.
For people who were nervous before starting, what helped you get through the first session? Did it get easier after that?
Also any tips for making the time go by faster during sessions? An hour seems long to just lie there.
Trying to go into this with a positive mindset but acknowledging I am a bit anxious about the actual experience.