1. It makes you lazy
There isn't much work to be done, both physically and mentally that have to be done actively when watching television. The only requirement basically is for your eyes to be open. With the invention of the remote, you don't even have to get up to change the channel anymore. Television makes you lazy because it does the thinking for you. It queues you when to laugh, cry, and think.
It's incredibly addictive, and the hours or even minutes that you spend in front of the television each day, can easily add up to years of your life being wasted. Ever wonder why people are able to watch episodes, movies, or even entire series of programs that they have already seen before? There's something that compels us to wanted to view the lives of others more than our own.
2. It's called programming for a reason
Televised programming is usually nothing like the real world, from fantasies, vampires, talk shows, sitcoms, and even 'reality television shows'. There's been plenty of studies on how television effects the brainwaves and and I think it should go without saying that, more than likely, one will not increase in activity by viewing television.
Although things may be stimulating for us to watch for a while, whether it be a movie or championship sports match, it ultimately doesn't challenge our minds to think.
3. It's bad to stare
Television is very fast-paced. I remember when I used to watch it often, regardless of the number of channels I had available through various cable networks, I could not help but keep having the feeling that there was never anything good on to watch. Like with many others that face a similar situation, it results in the constant flipping of tv stations. Not surprisingly this does not lead to positive mental stimulation.
How many people do you know that fall asleep while watching tv, or just sleep with it on because they are so used to having it on for most of their day? Some people really do turn into some kind of zombies, where they are unable to draw their eyes away from the television screen, only doing so during commercials to use the bathroom, or scarf down their food before their show starts back up.
Television has become a habit adopted by most today, but like all other bad habits, it can be changed and discarded with enough time, persistence, and determination. Slowly begin to change your habit of watching tv and you'll be surprised to see that you stop watching as much of it, than eventually, won't even care to watch it.