Many people look at dog training as a chore, something we drill, something that we don't really want to do, but we have to, something you don't want to make time for at the end of a long day.
But ... it doesn't have to be that way. You do not need to practice for hours on end. You don't need to drill your dog until both him and you hate it. You don't need to be serious. And yes, you can have fun.
I love incorporating play into training, it makes it interesting for the dog, and typically the handler is having fun as well. Teaching your dog to fetch or tug is a good start. I'm not going to go into details on how to do that here, but rather those are two games that you can reward your dog with.
For example, when I take my dogs out to play, I always add obedience to the play - be it the out for the ball/toy/tug, some simple sits and downs, recalls into a game, or heeling, it doesn't matter how, when or where we play, there is always an element of training. I keep it short, and I keep it fun. I don't drill the dogs, I let them enjoy themselves, I let them enjoy the training. I even run around with them myself (adds more excitement and engagement to the game) and I interact. I don't get distracted, I don't text, I don't have a conversation with someone, I don't throw the ball and then turn my back on the dog. I play with the dog.
It doesn't have to last long, 10 minutes of fetch or tug is more than good enough. You are able to get in repetition of commands, have fun doing it, and end on a positive. Even in this short period of time, you are benefiting both your dogs mind and body, you are teaching them, and they are learning.
It doesn't have to happen every day, a few times a week is just fine ... and no matter how much you work, you can not honestly say that you don't have 5-10 minutes a few times a week to work with your dog in a fun, engaging way that only benefits yours and the dogs relationship.
So get out, and have fun training!!