I loved this article from the Art of Manliness: Your Life Explained Through Dopamine.
The key is to toggle between these two sets of chemicals, as appropriate — allowing yourself to be satisfied, but never wholly so; content, and yet eager for continuous growth. You have to be able to enjoy the excitement of the conquest, and be able to hold onto what you secure.
Understanding the function of brain chemistry has been a huge part of the last few months for me. This precarious balance is crucial to master in order to find true happiness in life. One thing that I especially appreciate is the normalization of the ebb and flow. When we understand that force, we can work with it instead of fighting against it.