I never use the word heel as it is confused with here, a more adaptable command.
“Wait” will tell your dog to stop let you catch up. It can be interchanged with a short high-short low whistle as in Gold Wait.
(I do not believe that the 'Halti' style leads are a good idea, but short leads at about 1.5 metres long are the best.)
Your dog will pull on the lead as it wants to be the lead in your pack. In the wild this is acceptable. Think about dog sled teams, in which the musher wants the dogs to pull and encourages the dogs natural instincts. You are part of your dog's pack and it wants to impress you with it's ability to hunt. (It is after all a wolf in sheepdogs clothing). You will never take this instinct away from the dog – you will damage the dog emotionally if you try.
Psychology: You are only commanding it to wait so that it can work for your pack. You are the Alpha Male/Female and will never give this place to the dog. This position is earned by the dog who provides the food and shelter, so the dog already accepts that.
So, the dog is allowed to be a dog, provided it is safe to do so.
You are now going to familiarize your dog with the “wait” command. This is best started on lead. Walking with your dog means 10 – 30 mins (minimum) so that the dog can learn to wait whenever asked. You will use this command most of all on and off lead. You will also find that other members of the family will benefit from your diligent training.
You need to keep the dog's head level with the toe of your foot. You can have a loose rein, but with the hand on the dog's side hold the lead so that its head will not be able to go past the toe of your foot.
You will say “wait” when the dog tries to pull ahead. If the dog doesn't act, pull the lead across your front with the opposite hand, while saying “WAIT.”
You will not stop. After all, you need to get where you are going.
The dog will not want to go in front of you so he will hold back.
This method is a friendlier way to train. You will be able to master the “wait” command after a maximum of 10 days, probably sooner.
A Tip: When teaching this command you can walk close to a wall or verge. The dog naturally will want to stop and sniff, so you will allow this. But, please don't allow the dog to pee or defecate outside someone's front door. Take some bags with you, so you can clear up after your dog.