[QUOTE=slortar]
Oh, yeah. I was built like a medium-height stork when I was a kid (but with a bit of a belly). That lasted until about a few years ago when I started doing heavy compound stuff like squats and such, with the occasional foray into deadlifting. I’d say I have pretty muscular legs now. Nothing amazing, but I am definitely not built like a bird anymore, at least. 
The key thing for me was to eat a lot more, dieting off the fat regularly when that got to be a bit much and concentrating on heavy compounds, like squats (instead of, say, leg extensions).
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Along with bird legs came “sensitive” knees . . . squatting stresses them out. I do the leg sled . . . is that a decent alternative? The leg sled can stress my knees as well, but if I work my way up slowly and stretch propertly I can consistently use the machine.
What about your calves? Mine will develop over time, but both my calves and my forearms are really extremely thin. I generally try to do 4 to 6 sets of 10 down to 6 reps, but only once per week to maximize muscle gain. I do this for all muscle groups.
One thing that frustrates me is that I need to gain muscle AND lose fat . . . I want to do them at the same time, which means I need to really nail the nutrition side. I could gain mass by eating more, but I don’t want to gain fat.
One thing I do have which is a result of high school swim team (and subsequent focus do to motivation provided by noticable gains) is my chest. I have unusually large and defined pecs, especially for my body type. I need to get my legs to match because right now I have nice pecs, a gut, bird legs, and no forearms or calves. I need to balance everything out.
It’s really insane with my body type HOW LONG it takes with dedicated weight training to see significant results. Right now I’m in this pattern where I stay dedicated for about 4 months, which is right when I’m starting to really see some improvements, and then I fizzle out and lose most of my progress in a matter of a month or two. I really need to go the distance and change my lifestyle.