In response to a letter, the Rebbe writes: Concerning the blessing you received from my father-in-law, you have the choice whether to worry if the blessing will or won’t materialize — and when it finally does materialize you will be doubly burdened as to why you wasted so much energy worrying in vain — or you may choose to be strong in your faith and trust that G‑d will lead you on the straight path and fulfill all your needs. Then you will be able to say: look how well I handled the situation, that I didn’t worry about things there was no reason to worry about.

Igros Kodesh of the Rebbe, vol. 4, p. 256