Yup, 46" chest here...you're right about the lung capacity though. I remember back in school (I was about 9?) we were learning about lung capacity in Science...we all had to blow into this tube for as long as possible...then the teachers worked out our lung capacity from that.
I'll never forget her face when mine was LITERALLY double that of the guy in second place...
As far as looks are concerned, I just look big...on a 6 foot 5 inch frame, it just looks kinda imposing and.boss. Always funny when I turn up to a football (American Football) game at a place where we've never played before...they just kinda look at each other as if to say 'Damn, put 2 on him'

In the shoulder pads and chest guard, it looks even bigger!
Embrace the barrel chest...soon, when swimming is no longer an option, we'll be the ones free-diving for pearls

EDIT:
As far as fashion/clothing is concerned, I find that with a barrel chest, it's better to where slightly tighter clothes. Wearing baggy t-shirts will create a 'sloping' effect, where the t-shirt will kinda 'slope' off your ribcage and, instead of hugging/following your stomach, it's go off at a diagonal and make you look pretty chubby, even if you aren't. Wearing the slightly 'huggier' shirts/tees will accentuate your chest, but in the right way.
Whenever wearing a shirt or jacket, I'll
always wear a t-shirt underneath, then unbutton the shirt/unzip the jacket to just below my ribcage...that way, it's hugging the bottom half of the torso nicely, but it's releasing the chest so things don't feel too tight.
http://i286.photobucket.com/albums/ll100/Mightyracoon/26591_410136580445_581210445_550972.jpg - See how it hugs the body, but releases your neck and chest?
There are plenty more, but this'd just turn into the picture thread...you get the gist though, yeah? The collar frames the neck and head and further serves to make you look big, which is [u]good[/u[! Don't try to hide it, it'll just look like you're trying to hide fat or something. I find wearing a t-shirt underneath with a logo or a slogan is always good as it helps with the ladies...while you're chatting, they'll usually wanna read it and they'll pull your shirt apart to look...it's a way of flirting, and can tell you if a girl is interested

I'm no expert, but trust me, these things can help

There's nothing to be embarrassed about!