I have Chastity 8 and slept through the whole month of entering every day to the church and cant get it for some reason. While Haruto event triggers every third time I go eat.
Successfully triggered gym event starts with these messages:
"Chastity Level 1 event!"
"I wonder what the sermon will be today..."
"Excuse me, miss! My name is Agnes, and I'm hoping perhaps you could help me with something?"
Maybe you missed it?
Daily events triggers are reset through "Quick Sleep" action in the bedroom.
You can get the event by loading attached save (extract and replace files in save folder) and entering the Church of Fertility. If it is not triggered right away, just F5 and repeat.