Two things

Milo walks everywhere, but only when we're holding his hand. He stops routinely to ferret around on the ground, trying to eat gravel (it's impossible to walk up a gravel drive with him, he wants to eat each individual stone and will become so entranced by the scope and possibility of all the stones there are to eat that he'll sit right down and start sampling), pick up cobbles, generally poison himself.

He's happiest when he's carrying two things, one in each hand. He doesn't discriminate which things.