I don't care what my horse is complaining about, not eating hay, leaving friends, or going to work, when I'm leading them and around them for the few hours a day that I am, I am alpha mare. Walk beside his shoulder and flick him with the end of the lead rope if he doesn't respond to you clucking to get him to walk, then reward with a pat and a "good boy" when he moves.
I find horses that don't lead properly to be most insufferable and that's the first thing I teach anything I work with - how to lead and do it well. My horse, that I've owned for over 4 years, will walk beside me through anything on either side, and listen to my voice aids because he knows there is always a re-enforcement. And cookies in the barn :)
They say money doesn't buy happiness -- well happiness doesn't buy horses!