Teaching sit....to really sit

[Blessednewfy]

My guy is a 15month/male.....he sits when given the command inside but when he sees the leash,when its time to go out as he rather be free,he gets into a play bow and barks....when given the command sit he still barks.As I do not want him to think this is a game How do I correct this behavior to get a sit
Armand and Blessed the newfy

 

[Kodiak]

Have a treat handy. Use the come command and then make him sit in front of you. He should be more interested in the treat than barking. Riley never wore a collar or was walked on a leash when we got him and he would run into his crate when it was time to go for a walk. The treat, come and sit worked like a charm!