How about running some blues basslines? If you do the walks in position, you'll be working your fingers out. I'm talking upbeat blues

. Although, Crazy Little Thing Called Love has a fun bass line and it's a bluesy bass line.
If I'm feeling "out", I'll go learn part of a song I like to listen to-whether or not its one I'm *supposed* to be learning.
Try listening to music in a genre you don't usually, and try picking out the basslines....might shift the mood