Are you playing the right games with your dog(s)?
Different dogs get more fulfilment from some activities than they do from others.

Take Skye as an example, this is our family dog, she is a Working Cocker Spaniel, they are bred to use their nose to flush game.  I can play tug with her to a certain level but I have to make it easy for her or she loses interest very easily. Other breeds enjoy this game far more than she does. I can also throw a ball and let her chase it and retrieve it.  She likes this game a lot more than tugging but she finds other things even more fulfilling.

Skye's favourite activities involve finding things with her nose.  When we play searching games with her, she comes alive and her drive (motivation) levels skyrocket.  We are tapping into a deep rooted desire that has been bred into her over countless generations.

When we play the right games for that particular dog, we get breed fulfilment at an optimum level.  All dogs need an outlet for their energy and some dogs don't get enough fulfilment from walking.  This is why it's so important to understand your particular dogs physical and mental needs for optimum fulfilment.  This is a huge part of behaviour modification and should be the first step for any behaviour modification plan.