Just start doing it
NILIF isn't just about feeding, it's an entire way of life. Meaning that anything the dog
wants - be it food, to go out the door, to get on the couch, your attention, absolutely anything at all - needs to be earned. So before you dish out the rewards (yes, every one of those things is a reward), he has to do something to earn it first. A simple sit is enough (though you can ask for more when it suits you), but it just needs to be something that you ask and he complies with. Then you hand over the reward.
When it comes to food - it doesn't matter if he eats it or not. Just ask him to sit, put the bowl down - and if he hasn't eaten in 20 minutes, pick it up and put it away. NOT just for five minutes - put it away until the next meal time (and don't fill him up on treats in the meantime). If you consistently do that, he will learn to eat when food is offered (the alternative is to go hungry). It's natural enough that he doesn't view it as a reward nor something he should eat straight away if he's never had to - but if you change the regime, he will
come to see it that way.
