A monkey's dopamine soars when he finds a tree full of juicy mangos, but the good feeling doesn't last. The brain doesn't waste dopamine on the same-old same-old. It rewards you for meeting your needs.
When dopamine stops, you droop. We humans hate this droop and struggle to avoid it. Monkeys can help us understand its. A droop motivates a monkey to seek good feelings elsewhere. The loss of pleasure in mangos frees his energy to meet other needs.
Finding protein or social support revives a monkey's dopamine. But these are hard to find in the state of nature, and many efforts fail. A monkey wants to avoid failure, but he wants dopamine even more. So he takes difficult steps toward protein and social support instead of comfortable steps toward mangos. Each failure brings a droop but each renewed effort brings a dopamine squirt.
The brain is always choosing where to invest its energy. Monkeys choose without digital scheduling tools or a crisis of meaning. They accept their ups and downs instead of expecting to feel "up" all the time. If a monkey tried to feel good by doggedly pursuing mangos, his other needs would go unmet and he would end up in trouble. A droop motivates him to look elsewhere.