Any ideas for jobs to give my austrailian shepherd?

I have an austrailian shepherd. For those who don't know this is a type of dog that is bread for hearding sheep. The need a job to do. Lots of energy and major stocking and protecting of the families they live with. I don't have sheep. I have running shoes, a big neighborhood, a big yard, a big house, but not always enough time. I try to teach him tricks but he gets so food focused that age can't focus on what he needs to do first. I also think we over reward him and give him too much freedom. I want him to have a job to do because that is what he wants. Any ideas?