How a problem in your project change your mood

I was working on a problem on push-up notification in my app and for 2 days i wasn't able to solve it. I also do other things during the day for relax me, but my mind wasn't 100% present and free, i always think a about the problem in these situation until it's solved. How you manage problems when solution are not clear or immediate, or are not "just a question of time"? And your mood how change? Now i'm finally relaxed.