I stopped watching television when I got hooked on computers in 1994. At the time, my television watching habits consisted of about an hour of television per day. Since then my television watching habit goes in cycles of watching a lot of television at one time or going months without ever looking at a television. The times I do watch a lot of television it will be for movies. I have HBO and Showtime and those are the only channels I will turn on the television for. Otherwise, I tune out CNN, sitcoms, reality television, etc. If someone is talking about a show, I will have no idea what they are talking about.
I never really thought about television being a problem until I saw this site -
Kill Your Television TurnOffYourTV.com. After spending time on that site, I am more aware of how I spend my time watching television and what messages are being sent to me, both on and off the television. I think being aware of what is going into my mind has helped me.
As for how it affects Personal Effectiveness, I'd say it's about opportunity costs. The cost for watching television will be missing out on potentially more productive activities, and the cost for not watching television will be missing out on a mildly entertaining experience.