Is saying “Good luck” considered as shirk?

I have always thought that saying “good luck” to someone is considered shirk because I read about it years ago. Since then, I have tried my best to avoid saying those words, but it’s been pretty hard because everyone in my circle says it, especially when we have tests. I don’t know how to reply to them, so sometimes I just say, “You do your best too.”

However, last night, my class had a test, and my teacher, who teaches us about Islam, said “good luck” to us. Is saying “good luck” shirk or not or is it depends on our intention when saying it?