Why a behind position solves the narrow-path problem
On a path barely wide enough for two people, a dog walking at heel still blocks half the track, and a dog ranging ahead on a long lead turns every meeting into a tangle of apologies and wrapped legs. A dog who tucks in behind you reduces your pair to one person's width, lets walkers pass without stepping into nettles or mud, and keeps him out of the face of an oncoming dog who may not welcome a nose-to-nose meeting in a corridor with no escape space. It is also a calm position: behind your legs there is less to lunge at, and your body becomes a moving screen between him and the interesting world. Like any position, it has to be taught as a place that pays, not imposed by dragging the lead backward each time, which only teaches him that narrow paths mean being hauled around.
Build the position somewhere wide first
Choose a distinct cue word for the slot behind you, and start on a broad track or quiet lane where mistakes cost nothing. Walk normally, then give the cue and step across his line gently so he falls in behind, marking and rewarding after just two or three paces in position. Feed behind your leg or drop the treat at your heel so the reward itself lands inside the slot you are teaching. Repeat in short bursts scattered through an ordinary walk rather than drilling for ten solid minutes, which dulls any position. A light long line can help early on, giving him room to choose the position while preventing rehearsals of overtaking, but keep it slack; a dog held behind by tension has learned nothing he can offer when the line comes off. Once he slides behind promptly on the wide track and holds for twenty paces, the behaviour exists and only needs geography.
Transfer it to real paths and real passers-by
Move to paths a little narrower, then genuinely single-file stretches, ideally ones he knows well so the smells are old news. Increase duration between rewards gradually, and vary where the reward comes: sometimes a treat at the heel, sometimes release forward to sniff a hedge as the payment for a long hold through a tight section. Practise the passing sequence as its own drill with a family member playing the walker: you hear them coming, cue behind, step to one side of the path, keep paying quietly while they pass, then release him forward. Real encounters add an oncoming dog sooner or later, so keep early meetings to paths where you can step well off and widen the gap; a behind position beside a stile or gate pinch-point is worth extra rewards because the temptation to surge and inspect is highest exactly there.
Keep the skill polished on normal walks
Positions fade when they are only used in emergencies. Ask for the behind slot for short, easy stretches on every walk, a gateway, a bridge, a blind bend, and pay it often enough that the cue stays cheerful rather than becoming the sound of fun ending. If he begins creeping past your hip, that is information about the reward interval being too long for that path's distractions, not defiance; shorten the gap, raise the payment rate, and rebuild. Older dogs and very young puppies may manage only brief holds, which is fine; the goal is a usable tool, not a marathon. Note the cue word and the paths he has mastered in KinsLe's Care Teams so anyone else walking him reinforces the same slot and logs where he practised.