Same here, man. I've been 125 all my life, and then blimped up to 130 in my forties. Didn't want to go to a gym, for fears of high school P.E. classes being replayed... that and having an enormous tent in my pants!
But on a 3-month business trip to CT last year it was too cold to go jogging outside, so went to a Planet Fitness that the hotel had an arrangement with, to use the treadmills. Something told me to try the weight machines over in the corner, where they had a Curves-like circuit set up. I tried it, and liked it.
For the next year's business trip in several different cities, I worked out, simply doing 12 reps on each machine the gym offered. (Hey, I didn't know what I was doing.) Was able to up the weight every once in a while. This included naked workouts at the gyms in Pittsburgh and St. Louis!
About six months ago I found www.BodyBuilding.com which is not just for bodybuilders, but for anyone who wants to learn what to do in the gym. Click WORKOUTS over in the left nav bar, and look for Kris' 12-Week Video Workout, it is awesome. Then I found RealJock and their 12-week workouts also.
I'll never be ripped and buff like the guys at my gym, but I'm definitely bigger and stronger than I was, and have a lot more confidence than before. AND I still up the weight on each machine on a regular basis!