# Proving the Optimization version of a problem is also NP-hard

It is well-know that $$\mathcal{P}$$ and $$\mathcal{NP}$$ are classes of decision problems. I have proved that the decision version of my problem is $$\mathcal{NP}$$-complete. How to show that the optimization version of my problem is also $$\mathcal{NP}$$-hard?

I in advance thank you for any suggestions!