Learn about your dog's limits physically, take the heat into consideration, and have a time limit for your hike. If their tongue is hanging out of their mouth more than half way, it's a sign to stop and take a rest.
It's early in the New Year, and no doubt many have vowed to exercise and get into shape. But do you look at your dog and feel guilty that you're working out instead of playing with him? How about incorporating your dog into a cardio, calorie-burning workout?