The key to training is finding out what motivates your dog to want to do things.
It's great when food is the motivator and for some dog's it can be any food but for others, sometimes if the distractions around them are motivating, those treats need to be of a higher value. So you need to find out what food will your dog do anything for. It will be different for individual dog's just like people. The Birthday Cake needs to be saved for those highly distracting occasions.
What if your dog just isn't into food or has dietary issues?
Tug toys are a great way of interacting with your dog and rewarding good behaviour. Use a toy that you can play together and that only gets played with you. This is not a toy that they get at any other time and never get to play with on their own. That way it becomes a highly prized toy.
What if food or toys are a particular motivation?
Some dogs just love interaction with you their owner through touch and verbally. So lots of happy, higher pitched praise, belly rubs or pats can be just as rewarding for some dogs.
So one or all of the above work great when there are no distraction but remember if your dog gets too close to something that they find arousing it becomes extremely difficult for them to focus.
This is where you need to find the distance that you can still have your dog's brain even with the distraction around. For some dog's this may be a few feet and for others 20 or 30 feet. Whichever it is this is the distance you need to do your training at to be successful initially. Once your dog is able to do work at that distance comfortably, only then would you decrease the distance and it might only be 1 foot! Don't try to go too fast as any progress you have made may just disappear.
There is no quick fix, this will take time but it's about your dog learning how to control themselves around situations that they find highly stimulating. Only they can do this but we can guide them and manage situations for them to help them achieve this.
Some dogs are unable to focus in a class situation but by slowly being able to get closer to distractions such as other dogs and people we can eventually work them in our large indoor school at the other side to the main working group and after a week or two they can normally join the full group.