A Belgian is an active dog and needs exercise.
Usually, if there is another dog in the family and a
fenced yard, they will exercise themselves in play. If your dog is
an only dog, you will have to provide the exercise.
An excellent way to provide exercise is walking and,
especially, having your dog fetch balls, Frisbees, etc. Just be sure not
to over-tire a young puppy.
Never allow your Belgian to run loose unsupervised.
Remember, Belgians are a herding dog and might consider anything that
moves - including cars - fair game to chase.