The Rebbe firmly rejects despair, emphasizing simple faith that Hashem guides each person with Hashgacha Pratis and that all is for the good. Reflection on Chumash, Tehillim, Tanya, and Chassidus strengthens one’s spirit. Regarding a shidduch and past health issues, consult a doctor and a Rav. Blessings for good news.
https://www.torahrecordings.com/rebbe/igroskodesh/016/005/6070