My sister has a GS and the only way she taught him not to pull is using the halti. At first he used to try his hardest to get it off. Try putting it on when they are in the house so they get used to it. Obviously be careful they can't catch them on anything in the house and hurt themselves.

He is really good now and even without the halti he still turns his head to look at you when you pull him back lol.

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