The goal of this game is to associate a high-value treat with the phrase "Find It." If you practise it a lot, it can be a powerful focus tool in your arsenal when you're out on walks and need to get your dog's attention. It's also another entertaining and stimulating game that your dog will enjoy and appreciate you for.
First, choose some small tasty treats, such as boiled chicken fragments, dried snacks, sprats, or whatever your dog enjoys. Then simply drop a treat on the floor one at a time, saying "Find It" as you do so. Once they've mastered finding food on the floor, you should make it more difficult.
Drop the food into the grass so they have to sniff it out, or throw it between your legs so they have to keep an eye on where it is going. Maintain their interest in the game by keeping them on their toes.
If you want to push them even further, hide the treat behind a chair leg, in their bed, or behind their bed so they have to work extra hard to find it. The more of this you do, the more they will associate "Find It" with a fun and rewarding game.
Then, on walks, if your dog is pulling or distracted by a smell, simply say "Find It," wait for them to look at you, and then drop a treat nearby.