I had this issue recently (particular awful customer at work). Cross-training/yoga wasn't stopping me thinking about it, so I picked up a cheap punchbag and some gloves on ebay. It felt MUCH better doing an impact sport, and really going for it meant that I was exhausted in about ten minutes flat, so it solved any insomnia issues.
Lying very still and listening to some inspiring music on headphones can also help a lot. REALLY listen to it, focus on picking out the different instrument tracks, vocals etc. It's very immersing, almost like meditation. Tracks that build up to a crescendo work particularly well for me and it can be any genre. My stress playlist includes classical, techno, pop, acoustic singers, piano instrumentals, dance etc.
I'll also listen to songs and work out ballroom dance choreography for them. I know nothing about ballroom dance outside of watching Strictly Come Dancing/Dancing With The Stars by the way, but I find that just focusing on coming up with a creative routine in my head can be very repetitive and soothing.
Or, get a good book. Nothing stops me thinking about something faster than getting dragged into a great story.