It states (Tehillim 16:4), מהרו אחר עצבותם ירבו. The Beis Aharon zt’l discussed this pasuk at his tish, and he explained that the pasuk is urging us to be happy. After the tish, he called over three of his chassidim and asked them to repeat what he said. Surprisingly (and miraculously) each of them heard something else.
One of them repeated, עצבותם ירבו people are sad because, אחר, the parnassah that is destined to come to them later on, מהרו, they are in a rush to attain it now.
Another said, מהרו אחר עצבותם ירבו means that one sadness brings on another one. אחר מהרו, the next sadness is quick to come after the first sadness.
The nimshal is that people don't generally associate hardships with happiness. Nevertheless, when you know that the difficulties are a sign that something very good will follow, you will be happy with the hardships too.
