'intestinal fortitude'

In a nutshell, does 'intestinal fortitude' mean 'the ability to take a licking and keep on ticking'? In other words, an athlete can take a physical whipping or can endure almost anything without giving up.

Could you also say, 'He doesn't have the intestinal fortitude (guts) to ask Mary out'? I've heard the expression used like this, too.

Thanks.