So you want to do some cleaning up around the garage and you decide to move a table aside. But the table is attached to a board that's nailed to the wall. So when you give the table a tug, the board comes away revealing a rotted 2x4 under the window that disintegrates when you touch it.
So, ok, you think. You'll replace it.
So you go buy a 2x4 and cut it to size and smash away the old rotted 2x4 to make space for the new one but then you notice that it's not just the old rotted 2x4 under the window but also a trim stud nearby that's rotted, too.
So, ok, you go buy another 2x4 and an electric reciprocating saw and start cutting out the trim stud.
So you've removed the old rotted 2x4 under the window and you're in the middle of cutting out the trim stud when you notice the opposite trim stud is rotting, too. Oh, and so are the king studs on either side of the trim studs. Oh, and the cripple stud under the window sill? Forget about it.
Oh, and let's not even talk about the sheathing behind the studs.
Now go. You've got some work to do.