You can change your answer

You agreed to help on Saturday before checking the date. Now you see the commitment beside a long shift and an appointment you cannot move. The cheerful answer no longer fits.

Waiting until Friday will not make the change easier. Give the other person time to arrange something else. You can take responsibility without inventing an emergency to justify yourself.

“I answered before checking my schedule. I cannot do Saturday after all. I am sorry for the inconvenience.” If you can offer an alternative, name it. If you cannot, stop there.

They may be disappointed. You do not have to erase that feeling by restoring an impossible promise. Listen, acknowledge the impact, and avoid negotiating away a limit you actually need.

Keep a sentence ready: “Let me check and get back to you this evening.” It gives your calendar a place in the conversation before your answer becomes someone else’s plan.