Dogs with short coats require virtually no grooming, just a brush and wipe down every so often. Pet dogs with long coats require either regular clipping every eight weeks or so (where their coats are clipped short) or there long coats need to be brushed practically every day. Show dogs, or dogs with long coats, require daily brushing or else there coat will become matted and tangled. Not only can it hurt your dog if he has tangled and matted hair, but it will also become dirty and he will look shaggy and ugly if you do not regularly brush his coat.
Dogs have been selectively bred for thousands of years, sometimes by inbreeding dogs from the same ancestral lines, sometimes by mixing dogs from very different lines. The process continues today, resulting in a widening in appearance without speciation, "from the Chihuahua to the Great Dane."
Today there are over 400 recognized breeds of dogs in the world. Many of them have historical origins dating back hundreds, even thousands of years. Wherever humans have lived, dogs have been alongside them performing various tasks. One of the reasons dogs have been such a successful species is because they are so adaptable. They have made themselves useful in countless ways to humans so we kept feeding them, providing shelter for them, and, yes, breeding them. It’s no accident that we have dogs able to hunt, herd, guard, track, and do so many other things at an expert level. Humans figured out early on that if you bred dogs that were good at these things, you would get offspring that were also good at doing them. All of these jobs performed by dogs were necessary for our own species to survive. It’s no secret that we owe a lot to dogs, just as we do to other animals.
If you do not have time to exercise your dog daily with a brisk walk and lots of running choose a breed that does not have high exercise requirements. All of the breeds who require high amounts of exercise make terrific jogging, hiking, and ridding companions. So if you want your dog to accompany you on long runs choose one of these highly active breeds built for endurance and as much exercise as you can throw at them - they will love you for it (and a tired dog is not destructive).