My dogs just over two years old and he's only just started to master the fine art of jumping. At first he wouldnt jump anything out in the fields but he found it all to easy to jump five foot onto the garage at home, think it had something to do with jumping on rather than over. I kept plugging away at him just givin him encouragement at every oppurtunity which has finally paid off. He'll still try to find a quick way under though which i dont mind as i had a bitch a few years back which loved jumping but unfortunately skinned her leg and needed over 50 stiches, so im always on edge about it h