Monkeys respond to food with the same brain chemicals that humans have. When you know how these chemicals work in monkeys, it's easier to accept your own responses instead of being at war with yourself.
A newborn monkey gets a sweet, creamy treat when it acts on its sucking instinct. That triggers dopamine, the brain's way of saying "Wow! This really meets your needs. Get more of it!" Dopamine paves neural pathways that wire a brain to seek more of whatever triggered it. A little monkey seeks its mother the next time its blood sugar falls.
Cortisol rises when blood sugar falls. We associate cortisol with stress, but in the state of nature it warns of urgent survival threats. Cortisol works by causing a bad feeling. It motivates a mammal to relieve it, fast, whatever it takes. Dopamine can relieve it, so cortisol motivates a mammal to do things that have stimulated its dopamine.
Unfortunately, dopamine doesn't last. The brain saves it for new opportunities instead of wasting it on the same-old same-old. Fortunately, new things are all around a little monkey. Sitting on his mother's lap, he sees her put things in her mouth, and crumbs fall on her chest just inches from him. His mirror neurons trigger the urge to grasp one of these things and put it into his mouth like he's seen her do. When he does, dopamine! The good feeling motivates him to do it again.