Sammy WILD about leash up for walk time--really wild.

One thing that Sammy loves is his AM and PM walks.  So much so that when it's harness/leash time he is SO wound up with barking and bouncing that he can become dangerous to hands hooking him up.  The hands could be collateral damage LOL. 

It's obviously total excitement about the walk---or is it pooping?  Within just a minute of so on the walk we have pooping.  How do I calm him down without raining on his excitement or delaying his pooping? 

After a year of rescuing him he's becoming better and better adjusted but will always have some issues of trust and fear.