I honestly think for me it did all start with Trek. My parents were into Trek and so I grew up watching it with them and when TNG started it was the same because there was a new Trek series out!
I also remember watching Twilight Zone with my parents and Dr. Who (that was my mom's favorite show, still is) and movies like V: The Final Battle.
So I guess I just grew up in a sci-fi household. I got into Jonny Quest when I was just out of high school because I came home one day and my mom was watching the marathon on cartoon network while doing bills and i was like "What's this?" When i saw it again a few weeks later I was hooked (and yes I was like 18 and I'm still a huge JQ fan at 35, even have some fanfics written on JQ out on the interwebs).
So I guess between my parents influence and my love of reading that how it started for me. I still played sports and did all that growing up as well. Also played "war" alot with my older brother and friends in the woods around our house and wow...here I am, 35 and in my second real war.