//"I think he wants to drop the toy so he can have the treat in his mouth as soon as possible."//
See, i had the box RIGHT UNDER MY DOG'S MOUTH, so he could NOT miss. Soon as that toy hit the bottom of the box, CLICK/TREAT.
I handed the toy TO my dog, (at first) and i began with toys he already liked to have in his mouth,
when dog drops toy--->toy goes into BOX, yay!
see? dog does not reeeeally have to "hold" the toy, train him to drop the toy INTO the box.
Overtime, i began to move the box a bit to the side,
so now, Buddy has to turn his head to drop the toy in.
Overtime, day by day, i began to lower my hand holding the toy, lower,
and lower, so Buddy is reaching down to get the toy, to drop in the box, which is a bit to his side.
Overtime, in next lessons, i began to have my hand on the floor next to the toy, (instead of holding the toy) and now Buddy is now picking toy up off of the floor,
and
overtime, day by day,
i began to move the toybox over enough that Buddy now has to take a step to drop toy into box.
After he got that far, we progressed day by day, til Buddy is now taking two steps, or three steps, to drop toy in.
Then, i faded my hand next to toy, and
then, i faded my own self to being across the room, overtime.
slowly advancing along, so dog is moving to get the toy,
and also moving to drop toy into box,
BUT THIS TRICK IS SUPER EASY *IF* YOU START WITH TOYBOX RIGHT UNDER THE DOG'S MOUTH!! That way, the dog can NOT miss!
the dog does not much have to "hold" a toy, really. Focus on rewarding your dog dropping that toy into the box, and advance from there!!