I don't remember exactly when I stopped watching TV, but I suspect a big part of it was never really getting into the habit. By "not watching TV", I don't mean never watching anything at all, but rather not engaging in the habit of just parking myself in front of the tube after dinner and going from channel to channel, cold looking for that hero.
But by the ... late Nineties, I think? ... I was very conscious of how even a little bit of that a day was something like two hours out of my evening that I wanted back for myself. And given that I wanted to create things, those two hours would make all the difference for me.
Again, it's not like I never watch anything. I have Netflix, and I use it to get caught up on the occasional show that piques my interest. But it's not something I slide into habitually. Some of that is because the impulse to Go Look For Something Interesting To Put Into My Eyeballs has been eclipsed by the casual firehose of stuff washed over me from, say, Feedly or Hacker News or what have you. But a lot of it I can trace back to having developed a built-in resistance to letting TV suck blocks of time out of my day.
Some of that I credit to helping me also turn away from social media for the most part. The largest slice of that happened around May of last year or so, when I decided I wasn't going to bother reading Facebook or Twitter anymore. Posts made to my blog would get auto-echoed there, but I wouldn't open those sites on my own or interact with them if I could help it. That had a liberating effect on me of the same flavor as walking away from TV. Maybe even more so, because I realized the level of deep personal guilt that many people feel when they cut that cord was completely synthetic. I wasn't "shutting people out of my life"; I was trying to make the life I had all the less trashy and noisy. I was trying to make the experience of my life a little less like that of a couch potato in any form.
The people who matter still hear from me. I speak to them regularly outside of such channels. I think it's healthier to do it that way anyway. I call my folks weekly. I'm part of a circle of about half a dozen people who meet nightly, even if only for a little bit, to talk about what we're working on and where our lives are at, and we buoy each other up that way — directly, one to one, without too much else in the way if we can help it.
I'm convinced breaking a social-media habit may be more difficult for people than breaking a TV habit. The latter is mainly passive, and it's easier to push away something that's passive. The former is active, participatory, and it's easier to let it into so many more parts of your life than just a couple of hours after dinner or what have you. But I also suspect learning how to wean myself of one made it incrementally easier to learn how to wean myself of the other.