A shepherd breed is a subscription to daily movement. Collies and their cousins were bred to trot beside flocks for hours, and a dog bred for work will find work, ideally yours. The owner's back benefits, provided the routine is built sensibly.

How much exercise does a working shepherd really need?
More than a lap of the block. Most adults of these breeds want an hour or more of mixed movement a day: walking, trotting, sniffing, something for the brain as well as the legs. For the owner that is a guaranteed daily walk, which is precisely the prescription a stiff back benefits from most.
The trade is honest: you get a reason to move every day; the dog gets a body that lasts. Our guide to walking the dog as daily movement covers the human side of those miles.
What health checks matter for an active herding dog?
Hips, elbows, eyes and, in several herding breeds, the MDR1 drug-sensitivity gene. The shepherd dog health journal, written from twenty-five years with border collies and farm dogs, tracks the everyday side of that list: cruciate injuries, heat stroke in a dog that will not stop, and the supplements and weight management behind working joints.
A dog that limps changes your routine as much as its own. Soundness is worth checking before the routine begins.
Can you overdo it at both ends of the lead?
Yes. A collie will exercise itself and its owner into the ground if nobody calls time. Rest days, off-lead sniffing and shorter winter loops keep the weekly total kind to both spines.
What if your back cannot keep up today?
A garden session, a flirt pole, or a friend with a dog of their own covers the dog's side on a bad day. Yours may need nothing more than a hot shower and a short walk.
Some of these breeds also carry a gene that changes which medicines are safe, so routine treatments deserve a question to the vet first.
Sources
For the veterinary view on musculoskeletal health in dogs, see the British Veterinary Association.