Breathing tips and tricks help

The thing about acting is that it simulates real life.

"Theatre is about life, not lifelike." I can't remember who said it, but the OP has stated the medium is theatre. Stage craft and stage technique involved in stage acting isn't a simulation of life.

There are techniques and devices used on stage to achieve an effect that natural effort and displays don't achieve.

She is concerned that she cannot act out of breath for 8 minutes

A really good stage technique is to pant.
Exhale air, pressing with the diaphragm in short bursts, and repeat at the level of your own comfort.
Panting provides the impression of being out of breath to an audience, without being out of breath. And, you won't hyperventilate because panting focuses on the exhalation, while you completely control a minimal inhalation.

/r/Theatre Thread