I admire his courage. However, I still think he’s foolish to do such a thing. 

A.  Although I admire his courage, he’s a foolish to do such a thing.

B.  Though I admire him, I think his courage is foolish.

C. Though I admire his courage, I am a foolish to do such a thing for him. 

D. Much as I admire his courage, I am a foolish to do such a thing for him.