Hello my name is Annie. I'm a 15 month old labrador retriever. I love to run and fetch balls, knotted ropes, stuffed toys, hunting dummies, etc. I can do this for hours. Or so I think. Just like you, your four legged friend can benefit from an exercise routine. Notice how I said "routine." Regular exercise is the key. Don't take your puppy outside for 30 minutes one day, then ignore them for the next several days. Regular play sessions help build up muscle tone, joint flexibility, and cardiovascular fitness. I always enjoyed short 10 minutes walks when I was young. We extended the time as I grew. I also suggest swims in shallow water. This can be very refreshing and won't be an issue in very hot weather.
Remember to keep an eye on your puppy. Always be aware of their body posture. He he/she excited? Tail wagging? Running boldly? Making eye contact? These signs show their masters that they are having fun and have enough energy to commit to the activity. Be on the look out for a puppy wanting to walk away from you, or wanting to lay down. Another characteristic of a tired pup is yawning and avoiding eye contact. YOU are the adult, and need to shorten the play activities BEFORE the pup gets disinterested. Keep the pup wanting more!