Subject: Thank You for Inviting Me!
Dear Cindy,
Thank you so much for inviting me to go swimming tomorrow at 4:00 PM! I really appreciate it, and I would love to swim with you.
However, I won’t be able to join you because I have a family commitment at that time. I’m really sorry to miss out on the fun!
Can we plan to go swimming on Saturday instead? I am free at 2:00 PM, but if that doesn’t work for you, let me know what time you prefer!
Thanks again for the invitation, and I hope we can swim together soon!
Best,
[Your Name]