(the, hopefully, abbreviated version of my weight-training journey: I've written this before on the forums somewhere !)
I was not at ALL athletic/active as a kid. What one would probably describe as 'frail,' weakling, scrawny, and always picked last in gym class... until about 14, when I chubbed out a bit.
When I started working at a food coop in college, I helped unload delivery trucks and stock. One day, I was carrying in two, 25-pound bags on my shoulders, and after I set them down, a couple of people asked if I was okay. I was puzzled, and said "sure. why? " They said I'd just carried two, 50# bags. I didn't believe it, but sure enough , I had. And it hadn't been that hard.
That was my first inkling that I wasn't a wimp/weakling. I impulsively decided to start lifting weights: bought a 120# (?) set of weights from somewhere like K-Mart (and had a heck of a time moving it myself first into and out of my housemate's car, then up the stairs to the room I was renting), and did a bit (luckily not too much, or I'm sure I would have injured something the way I injured my knee when impulsively taking up daily running up and down hills!).
Skip forward to grad school: I decided to take a weight training class. One day, the instructor was gone (he was a coach, and had an out-of -town game) and a woman instructor took his place. She went around quickly to each of us as we made the rounds of the equipment, correcting our bad form ( form that could have gotten us injured).
After that, I decided I couldn't trust the regular teacher (who hadn't given us clear direction nor corrected our form), so I picked up a Rachel McLish book and Arnold's Encyclopedia of Bodybuidling and started reading on my own, and going to the gym at other than class time).
For the next 2 years, I visited the weight room regularly, then got off habit when I started studying for prelims and writing my dissertation. I biked and walked a lot, but didn't do weights.
I didn't get back into weights until 2 years after I started teaching (afterr stepping on a scale one day and realizing I'd gained 10# in those two years: I refused to let things keep going in that direction!).
I got back into weights slowly, starting with some 5# heavy-hands and some Kathy Smith/Jane Fonda workouts (circa 1992), and kept moving up in weights and in difficulty of workouts.