About 16 minutes every 24 minutes of every day, I need a new desk chair this one is a pre-WW2 japanese torture device. I'm only not in front of a monitor / television screen when I go out, and I haven't been doing so regularly recently, money and friends being in different cities for university (can cost over £20 to see some of them for the day).
I split that 16 minutes wisely into gaming, internet wandering, gaming, TV and gaming, with the other 8 minutes used to hallucinate vividly in a coma and then develop sudden amnesia.
Although I somehow get time to read every night for an hour, but that's still sitting on my arse and I don't think the screen changes much to my blood pressure.