The Miniature Schnauzer dog breed is a very high energy breed of dog and do require a good amount of exercise to burn off that energy and stay health.
All dogs need quite a bit of exercise to stay healthy and live a good long life just like us humans need plenty of exercise.
Dogs including the Miniature Schnauzers are a big commitment so you need to have time to devote to the dog to keep them healthy and keep them from developing health problems.
Try to walk the dog at least once everyday for at least 20 minutes at a time and you'll both benefit by getting exercise.
If possible let the dog run around in your yard and play ball or something with it as well.
If you exercise the Miniature Schnauzer enough it can live as long as 15 and even 17 years.