Letting It Fly 

to do something with a serious risk that would reap an equally serious reward if successful

If someone risks his career for a loved one, that would be letting it fly.

If someone takes a shortcut while driving by quickly going the opposite direction on a one way road when time is of the essence, that would be letting it fly.

similar as to throw caution to the wind

Letting It Fly by Nathaniel Bacon March 13, 2009