When the project focus picker strategy is turned on you get this prompt every day:
Clicking on the "Pick Projects" button allows you to select the projects you want to focus on today from a list of all your projects:
To pick a project, just click on it to highlight it.
Filter and sort
You can filter this list on the top right to make it easier to find the project you want to focus on today.
The selected projects will show at the top of your day with their project radial.
Clicking them takes you straight to the project overlay where you can work on the project in a focused way.