Okay, so I'm a huge Superman fan. I have been ever since I was a small kid.
One thing has always burned in the back of my mind though. For him to be as invulnerable as he is, his body matter would have to be incredibly dense. So, with that in mind, how did he get so muscular? He would have to be bench pressing skyscrapers to get a work out.
In reality, it is one of those things you have to suspend your belief in reality on, but I do think about it all the time when reading Superman. LOL