Two modes for me.
1. Trying to relax, paint some models, mellow out, unwind ---
Enya. Ya, you heard right. This is when I paint one or two models to the nines and work on my technique.
2. Trying to get work done, gotta finish by a certain time, doing something repetitive -
Ron D. Core. Look it up, it's worth the money to buy the album 'Psychotic Episodes', if you can find it. 'Decibels of Destruction' is good too. Nothing better to get you grinding your teeth at 200+ BPM. I get a lot of boring stuff like base colors and so on done in this mode. But, I did used to fall asleep to the static channel or test patterns in the days before satellite TV.
-Dis.