Today I gave my dog over 2 hours of exercise, he's 5 months old. I trained him for 15 mins, then a 30 min walk. After, I took him for an hour's walk with some flirt poll action and some socialization. He slept one hour after and then ran all over the house. Then I trained him 30 more mins at night with another 30-minute walk, which he was not tired! Is this normal to have so much energy and not be tired? I know gsds have insane levels of energy, especially puppies, but mine never gets tired.