Some days when your out there with your camera there is absolutely noting to shoot. Or perhaps you just don´t see it, or it could also be a lack of imagination? What ever the reason It´s kind of boring on your lovely day off. When you experience this mood in Street photography there is probably a lack of imagination if you don´t count knowledge.
The best thing in my opinion is to a immediately let go of your expectations and do something else or shoot something else for a while. And if you experience the same thing repeatedly? Try a photo workshop on the subject or any subject as a matter of fact. It will probably cast some new light and give you enough inspiration in some direction!
One of my workshops is about Portrait with a model on location. This is really awesome and you can certainly use the knowledge for every motiv category that includes people and environments in a much more quality way afterwords!
In order to be faster as a photographer and to able to build up more interesting images you need to be more a where of every component of your motive category, learn how its shaped, what it´s used for, how it works, moves and what to expect basically. There is not so much to it and it will probably help if you are a bit curious as an individual. It´s necessary to place everything in a certain logical order using composition to make it look good in your final display!