Outside the back kitchen door of Haven is a pathway to the freshwater spring where Mira gets her water from. This place also happens to be the only place on the entire property that fighting is allowed.
The canyon that surrounds the rest of the inn opens to the west and east to forests (though the western side does eventually give way to more rocky terrain a ways past the spring).
There's even some training exercise equipment and some nice picturesque forest to have a fight/training montage in.
So, when Mira says to take it outside, take it out here and have at it.
