When my mind is scattered, anxious, or I just can't focus, my go-to are these "crazy doodles" as I call them. This one was huge therapy for me.
I started it at home and finished it up at my office these days, my favorite local coffee shop...
If you are at all a doodler (or even if you aren't!) I really recommend trying this exercise. Pick a few shapes and fillers and don't think too much about it. You'll be amazed it what the finished product looks like...I was with this one!