have you taken him to obedience classes?
there are some great ideas on this forum of how to train, do fun things, AND even retrevial work.
I know we all have limited time...but sometimes it only takes 15 min a day to teach them a trick.
It seems the hardest thing for me to get my dogs to do is come EVERY SINGLE time I call - NO MATTER WHAT.

They are all reasonably good separately - however add another dog or more...and I may as well not even call them...unless I have their favorite treats.