Former Ugly Duckling here as well. I started going to the gym after a cycling accident. Cycling was my only physical activity. It didn't give me any definition, but it did allow me to shed winter weight. After the accident I didn't want to get back on the bike.
Started with the gym just to keep my weight in check. At the time, and even before, I had no shape to me other than what gravity provided. I started enjoying it mostly because it was something to do that was different, and for the mental space / agility it offered. It still is the best means for me to de-stress.
I'd witness the other guys at the gym - watching to see the ways in which they were working out. Looking for ideas, pointers, etc.... Yes, many of them had great bodies.
Over time my body began to change. I am by no means some muscle god, but I now have some shape and definition. I get attention that I would have never anticipated in the past. This combined with the mental benefits has changed my outlook on just about everything...work and social.
I don't only look to muscular guys with whom to socialize, work, date, or hook up with. There's a ton of great people in this world. What I have come to realize however, is that I much prefer guys who understand that taking care of themselves physically (and mentally - because who wants to hang out with a dolt?), is an important part of longevity.
Being muscular is not the only way to be physically healthy, but it is one indication. Runners and swimmers are in great shape but not necessarily muscular. Still, I know that these guys are balancing their lives in a way that makes them happier and healthier.
It's this mindset that I find attractive and not necessarily the muscles. The spirt of a man is by far his most attractive asset. In many instances, however, its the packaging that catches the attention. Ideally, you'll find something really good when you open it. Sometimes, however, it's just something pretty to view and nothing more.