Do pets enjoy exercise? You bet, just ask anyone who started asking their dog if they wanted to go for a walk and what happened from then on whenever the word - walk - was uttered. Some dog's even fetching their leash anticipating going for that walk.
The biggest issue about an exercise program for our pets is getting them started. Never, never decide you are gong to exercise your pet cold turkey. Pets and people require a warm-up before the exercise begins. And, pets, like people, should be started into a program slowly, building up to the level/duration of exercise that you prefer and that the pet responds to.
If puppies are given proper nutrition (a top quality growth food) and an opportunity for plenty of rest they'll be full of play. As they grow older outgrowing this playful period it then becomes the responsibility of the owner to see that they get plenty of quality exercise on a regular basis.
Walking is great exercise for you and your pet and can be as long and a strenuous as the two (or more) of you determine. What's important is that it becomes a routine that the walks are done on a regular basis. Regular means every couple of days at the least and more if it fits into your overall schedule. If you are tired of walking and your dog still wants to continue then a game of fetch, chasing a ball, going after a toy can finish out the program for the day.
DO warm the pet up before undertaking any exercise
DO have K9-Quencher, or water available after a workout
DO make the exercise a routine happening - pets thrive on consistency
DON'T over do it
DON'T feed immediately before OR after and exercise period
DON'T exercise your pet outside on extremely hot or cold weather.