Age 16
Today -- or as the clock/diary turns (23:55 here) -- we start our sixteenth year, so I've looked at some old archives, trying to find photos of me aged 16 (some time after I had begun programming; I actually messed around with scripting at somewhere around the age of 12 or 13).
I was introduced to GNU/Linux around 1998 when I was 16. A friend of mine (and a geeky classmate) called it "Linux" and was using it on his PC. Back then, many people including myself were using Windows 95. A couple of years later, as soon as I started studying at the University (aged 18), I move to GNU/Linux. It was Red Hat with GNOME and KDE. Later I experimented with all the other (existing at that time) desktop environments/window managers and settled on Enlightenment for a while. Back then, by GTK and Qt standards, Enlightenment was actually very good. I used NEdit (it's still available and is actively maintained). It was good for development and for note-taking. Later I started using LyX (around 2001) and then raw LaTeX as well; I didn't like Abiword because it wasn't suitable for scientific publishing. My introduction to GNU was around 2001 when I was developing with GTK. I started to get a better grasp of the real history and the underlying philosophy. I then got back to USENET and IRC (which I had already used as a teenager) and a lot of my GNU/Linux advocacy started in newsgroups (before social control media like Digg.com became a "thing"). That was in my early 20s. At age 21 I started my Ph.D. (I could leap past a Masters degree because of my grades) and chose to work on it under the supervision of the person who would soon become the head of the Computer Science department. He was very demanding and had strong work discipline. I learned a lot from him.
Here we are all these years later and I focus a lot on software patents, if not patents in general. In that domain, there is a massive vacuum in the media; it's like there are no journalists left to actually fact-check these matters; operatives of the litigation industry don't quite count, as all they do is churnalism (many examples of this in today's Daily Links).
I didn't plan to do activism or journalism or censorship-resistant publication (essential for vulnerable sources/leakers/whistleblowers). That just happened along the way. It's rewarding in every way except financial. ⬆