How can you make a golden retriver lose weight?

With any dog, feed it only the amount of low-fat dog kibbles that are recommended by your vet, or by the dogfood company. No 'People' food at all.

Goldens are big dogs and need to be walked or run for half an hour twice a day minimum, and romped with in the back yard or in a field, etc, for at least a half hour a day.

Every day.