What does it mean if your dog has "low motivation?"
It's not the end of the world if you hear a trainer say that about your dog! Unlike a child whose "low motivation" might predict years of difficulty and poor performance in schools, dogs with low motivation are often very successful at being great pets, and behaving just fine.
Dogs who have high motivation are usually the ones who pull on the leash, steal food, and jump all over you for attention. They want stuff, and they're not afraid to go and get it, even if this means getting in trouble or going against the wishes of their owners.
Dogs with low motivation may enjoy a snack or a sniff, but they're not willing to expend too much energy to get it. If they want something, it's not too hard to convince them otherwise; a quiet "no" usually does the trick just fine. They are frequently calm and compliant in everyday life; this is the type of dog who does not seem to "need" training -- they already behave pretty well. They're not motivated to get anywhere fast, so they rarely pull on the leash. They're not super-motivated to get food, so they stay off the kitchen counters; they like attention just fine but won't jump all over you in order to get it. Nice dogs, right?
Many trainers, high-level competitors and more active/advanced owners, however, feel that dogs with higher motivation are easier to train and will often intentionally seek out a "naughtier" dog, searching for a naturally energetic companion who will enough internal drive and motivation to work hard to earn rewards. If you want the type of dog with this kind of motivation, but don't have it, there are some things you can do to improve motivation.
First, and this should hopefully be a given, make sure that your dog is in good health. Things like sore muscles, bone/joint problems, poor nutrition and obesity can cause what looks like low motivation. If you are in any way suspicious that some of your dog's unwillingness to work may be caused by something physical, then check with a vet.
If your dog's healthy, one way to help build motivation is to be more reserved about allowing your dog to access "free" rewards. Dogs who are free-fed (food constantly in a bowl that they're allowed to eat of whenever they want) for example, are usually not very motivated to work for food, because food is free and always available. Regular meals, where the dog is conscious that you're the one giving the food, can help. You can also start asking the dog to do something vefore you give it a toy or initiate play -- a "sit" before you throw a ball can go a long way in raising a dog's motivation.
Slowly, over time, many dogs motivation improves if you simply continue to work at it. Even if a dog doesn't particularly care about treats, if you make it about more than just food -- the interaction with you, the praise, the "earning" something -- gradually the dog will start to enjoy it more and more, and motivation should improve. You can also try blending treats with play (tossing treats, etc) or with verbal praise/petting/interaction, to see if that helps.
Increasing a dog's motivation can take a while, but it's usually doable!