Poll: I have half a mind to do it.
I have half a mind to do it.
This is a very tricky one for non-native speakers!!!
Having half a mind to do something has always struck me as implying the unspoken words "but I won't." behind it. If I am to do something I have a mind to do it, or I set my mind to do it
Here is my interpretation: I'm almost inclined to do it.