It's an important distinction to make that the fight or flight response is only good in short bursts - an intense, acute, short lived spike in adrenaline, etc.

When it's a chronic state, the body can't handle the amount of constantly ramped up intensity. Chronic stress indicates deeper health issues, and should be fixed out at a root level. Functional medicine focuses on uncovering the root cause.

Fight or flight responds to perceived threats - your body is trying to Treat symptoms first and find root cause later.