If my dog is overweight, what is the safest way to exercise them to shed pounds?

Slow and steady. Work with your veterinarian and talk about a diet plan for your dog. Also work on an exercise routine that includes short walks that keep getting longer and longer and more frequent, until you get to the point where they can do a bit more aggressive types of exercise, such as running and jumping, because you don't want to hurt their joints by having too much poundage on them.

Start slow, especially if it's hot outside. Begin with a short walk to the mailbox and back and gradually increase the distance each day. Ensure you have plenty of water to prevent overexertion.