Thread: Focus?!

I have a 2yr old ESS who in the yard retrieves well delivers to hand etc. When I have taken him to training days he seems to perform really well and is switched on however when we go to the park for training all he wants to do is run around and chase things. He seems to forget any whistle commands and just takes off! I have run him on a long line in the park and he works ok but is really distracted and doesn't focus on me at all. He shows no interest in retrieving a ball / bumper or anything
Don't even get me started about what happens when we go on the beach!
It seems he needs other gun dogs around to switch on however this is not always a viable option.
Any ideas or tips? Especially to get him focussed on me.