Thanks for the comments.
Interesting, I'm a big guy, and there a ton of very heavy, out of shape singers that can sing all night, so I don't agree about the being a runner or swimmer thing. BUT I agree any excersize is good for the body and could only help overall.
I took voice lessons in my teens, no problem with the breathing. It just seems my voice after a while singing, tends to get lower, due to the throat muscles getting relaxed. This is normal for singers. My voice or my throat tends to get dry, scratchy over a period of time. Usually starts to kick in about an hour or so into a gig.
When I sip warm water, it helps the situation but I could of sworn I read "somewhere" about a liquid that when sipped on in beteen songs, helps soothe the vocal chords, keeps them "healthier" during a gig. I'm thinking it might have been warm tea with honey. Can anyone comments on this? Thanks.