When training obedience heelwork whether in a hall or field etc. Don’t just march saying heel and hope the dog keeps with you, unless you have his full attention he will soon get board or start wondering .
I’m not so keen on the “watch me” word I like using the “close” which means near to my leg and concentrate on me.
To start have him sat by your left side, get his attention Then “close” (move off) 2 steps and “sit” making sure you’ve got his full attention in the 2 steps. (And treat if he’s got it right) repeat 2 steps etc.
After you repeated 4 or 5 times and you’ve kept his full attention move the pace to 3 steps and keep building the steps up BUT DON’T BE IN A HURRY 2 GOOD STEP ARE BETTER THAN 5 BAD ONES.
All the above is not covering corners & turns etc. which is another exercise