I'm going on a 4 mile walk to raise money for homeless pets this weekend. Dante has been training for 2 months (1 mile walks, then 2 mile walks, plus puppy agility). Has anyone taken their pup on a long walk before? I'm a little nervous. He was born January 19th of this year, so I don't know if he's 6 months yet, or almost 6 months. any input?!!! Thanks!