This is a very broad question, and one that keeps spawning smaller, related questions the longer I think about it. Personally, I rely on aggregators such as Hubski, Hacker News, and to an ever decreasing extent Reddit to find new content. But I almost never post to any of these sites because the majority of the content I enjoy was found on at least one of them and has already been reposted on the others. I imagine the people who post more often must either be very quick to share new discoveries or else spend a great deal of time combing through the miles of less interesting stuff. Then this morning, I read this post by goo and it made me wonder if it's just a personality difference.
Ultimately I strive to be a less passive member of Hubski, but I never want to post just for the sake of posting. But the obstacles to finding content worth sharing continue to mount. Mainly it's about a lack of time, and an aversion to being bombarded with ads.
So how do you find the content you share? And what motivates you to share it?
I check out stuff. A lot. I have a few sites I regularly frequent, such as Speedhunters, Hooniverse, The Truth About Cars, Vice's Fightland, Bloody Elbow, and a few others. I've also gotten into watching quite a few Youtube channels as well.
If you ever looked at the post/comment history on any of my profiles on any of the websites I've been on over the years, you'll find my comments far outweigh my posts. I enjoy conversing with people significantly more than I like to share. However, when I do decide to share something, it has to fit in one of three criteria. It either has to be A) immediately topical so I know it's something people want to see, B) something that is in depth enough to have substance behind it, but also be decent in quality and easily accessible so that people who don't have an immediate interest in what I want to share will appreciate it, or C) something that's esoteric but so awesome I think that anyone who loves something that esoteric will appreciate it. Every now and again though, I'll post something stupid just because I think it's fun.
As for Hubski in particular, I'm going to focus mostly on posting things about cars and martial arts (pretty much MMA and Boxing) partly because I feel like there's a dearth of that content on here, but mostly because I think they're absolutely wonderful subjects that I'm passionate about and I want to share. There are a lot of other things that I enjoy that you'll never see me post on here though, mostly because they're so esoteric I don't think anyone would appreciate them.
So yeah, in short, I find content because I have an internet life outside of sites like Hubski and Reddit.