I don't have yet a car (much more if I have one)and my work ends around 2:30 PM. When I get lucky,I get out exactly that time, but if its a busy day I stay until 4PM. I still get to do a lot of stuffs to keep those idle moments occupied.

They offer yoga class in Sheraton every Sunday... That's one nonboring to do in Doha, (everybody should try it)Jogging in Corniche,that is another- and least expensive. Practice tennis at Khalifa.