By active I mean actually coding. I usually have a side project or two that I'm working on (although sometimes barely at all) and I try to pick projects that involve working with a tool, platform or skillset I haven't tried yet. That's how I've gotten into things like deep learning, computer vision and 3D graphics that I wouldn't normally get to use at work.
By passive I generally mean podcasts. As a front end developer, I recommend Shop Talk Show, DevChat.tv's podcasts, Toolsday and Codepen Radio (and for people who are new to CS entirely, Base.cs is an awesome podcast). I'll put one of these on while driving or playing a zone-outable video game and just absorb.
I suppose I should also recommend things like Pluralsight and Lynda.com for getting an introduction to a topic I'm completely unfamiliar with. These are invaluable, but only if combined with actual experience in the thing you are learning. If I take a course on there and don't apply it soon after, I'll generally forget most of what I learned.