At work I frequently heard:
“It’s easier to apologise than to get permission.”
Yes, easier for you possibly, but not for the people whose time you wasted by your selfishness and professional incompetence.
In my rock and roll social life (on Facebook) I occasionally see:
“I’d rather regret the things I’ve done than the things I haven’t done.”
Society must stop rewarding people who’s doing only “does unto others”, so they can be “successful” or “cool”.
On The Outside 
“It’s easier to apologise than to get permission” is perhaps more applicable to situations with one’s other half :p