One of the books I've been reading for work recently is CTRL-Shift, a collection of improv games for working life. I've had it for a while and flipped through it often, but there hasn't seemed like a good time to try any of the suggestions in it -- not enough time or other resources, usually.
Today, though, felt like a "stuck" day, and I was in a terrible mood, so I tried the acronym game. This involves nothing more elaborate than writing down acronyms that one encounters in daily life and thinking up new meanings for them.
I don't know how "useful" it was, but the exercise in silliness broke up some of the clouds on my mood.