Wow… how do dogs have so much energy?!?

I have a 14-week-old puppy. Husky/Chow/Pitbull mix… (He looks just like a husky with black husky markings, but floppy ears) …So, anyway… I just walked him for 50 mins. I walked him, and even ran a few times and gave him a real workout… but how in the world does he still have energy left? He ALWAYS starts pulling towards the house when we come near it, and he’s tired out, yeah, but if he finds something interesting, he’ll just perk up as if he’s not tired at all… -.- I think I’m gonna need a doggy backpack when he gets older. XP I bet that’s still not gonna tire him, though…. So, how do they have so much energy? =P

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