In low spirits
Lydia: I’m coming from Mary’s house.
Sheila: How is she?
Lydia: She is low in spirits.
Sheila: Why? What happened?
Lydia: She didn’t get through her exam.
Sheila: Oh, I’m sorry to hear that. Explanation: Low in spirits/In low spirits - feeling sad
Example: I’ve been in low spirits (feeling sad) lately.