Here's why:
* Meaning: "Incredibly fit" refers to physical condition. It doesn't make sense to describe a play as physically fit.
* Grammar: The sentence is already complete and grammatically correct. Adding "incredibly fit" would make the sentence grammatically incorrect and nonsensical.
To make the sentence more descriptive, you could consider using an adjective that relates to the play's success, such as:
* The play was incredibly successful.
* The play was incredibly entertaining.
* The play was incredibly well-received.
These options provide a clear and relevant description of the play's success.