Working with initial and boundary conditions in PDEs

Hello,

I have this problem:

A homogeneous body occupying the solid region D is completely insulated. Its initial temperature is f(**x**). Find the steady-state temperature that it reaches after a long time. (Hint: No heat is gained or lost)

From what I understand the initial condition is written as

and since the region is insulated the neumann condition is interpreted to be

At this point, how would i a derive a means to define a steady-state temperature?