When you make your living from "grinding" at the poker tables, it's very important that your playing conditions are as ideal as possible. This includes:
Allowing yourself enough time to play.
Not just a quick 30 minutes here and there which encourages "gambling" rather than the patient play that is required.
Playing when fresh.
If I'm feeling tired then I won't play. Instead I'll often sleep for a while until I'm ready to play.
Playing without distractions.
I'll rarely play when my two daughters are running around the house- even when their nanny is here. I'll also often turn off my phone and MSN. (Due to the monotony of multi-tabling full-ring for several hours at a time, I don't consider having the TV on as a distraction- and will often get through 2-3 films during a session.)
Sometimes I have to leave my daughters on the fridge to avoid being distracted!