Tommy is adorable!
I think dogs have to be taught how to have fun. We plucked them out of their natural environment eons ago, so they don't instinctively know what to do with their energy -- or lack of it. Some dogs get in trouble because they have too much energy and don't know what to do with it other than destroy things. Other dogs can get lazy because they don't have to work for their meals, so they really don't HAVE to do anything to survive. Shoot, I'd be triple my weight if that were the case with humans.
I'd suggest trying to teach him how to play. Try different toys, and don't expect him to play with it on his own. Play tug of war, try fetch. Use treats to reward the kind of responses you'd like to see from him. Buy an interactive toy where the dog has to work to get a treat out of a toy. Make yourself part of the game.
And start a daily walk. Once you develop a toy drive, take a toy on the walk to make it more interesting. Bring treats on the walk. Let him sniff stuff. If you make it fun, he'll start looking forward to it. I find doing activities at the same time helps. Walk first thing in the morning. Then breakfast. A trip outside for potty. A long day while I'm at work. Then either games or tricks in the evening or another fun walk.
As for obedience training, find someone who teaches positive training methods and start right away. If the instructor knows how to keep the training positive, it should improve your bond with your dog. Talk to the instructor before the class begins and let him or her know what you'd like to accomplish in the class. Maybe they'll direct you to another type of class that's designed for fun.
For tricks, buy a book or look for instructional videos on youtube. Here's one book I liked. Some of the tricks are geared for bigger dogs, but there are many a little dog can learn.
101 Dog Tricks - Training Books - Training & Behavior - PetSmart
Good luck. Have I said Tommy is adorable yet?
