Not at all.  It’s easy to understand why one would think a Greyhound would need a lot of exercise. After all they are the fastest on the planet. However, even at the racetrack the race is a relatively short. This print for short distance and they are pretty much done. Moderate exercise is all they need to stay healthy. A couple walks per day is really only need.  Though, they do enjoy running. Even if you have a small backyard they will be able to run and enjoy themselves. I like to take mine to the dog park periodically just to see them run.