Trouble training a grey hound, please help?

it sounds like hes very frustrated, i have a collie greyhound cross and they need at least two hours walking every day, with lots of running. greyhounds are known as 30 mph couch potatoes as they have a mad half hour when they run like crazy and then sleep all day and are very calm with the right exercise. it is not fair to get a greyhound and then say they are untrainable because nobody takes the time to look after them properly, going out in the garden is not a walk he needs to go for a good long run out in a big field.