Let me give it a try: "所有我已失去的東西當中, 我最想念的是我的理智."

字面意思是：在我失去的东西里，我最怀念的是我的思想。但这样翻译并不美。 个人认为这样好些：我可以失去一切，唯独不能失去思想。

I like this sentence. It kinda reminds me that those who are trying so hard, fighting so hard, competing so hard in the materialistic world, but might gradually get lost...kinda like a dead-alive-person...because lost mind...jaja.. so I would translate it to: 一无所有后，我最想找回原来的我（just personal view) literally :所有失去的东西里，我最怀念的是自己的思想。I think it also make sense.

Hi! Im really surprised! For u look way like a chinese! Who speak english.(^_^) lol. 在所有失去的东西里，我最怀念的是我的回忆....right? Lol

穷且益坚,不坠青云之志 lol, that's my answer, counterpart proverb , i make it in a little bit funny way.