Animals don't think something is wrong with the world, despite their survival challenges. Reptiles have thousands of offspring and most are eaten by predators. Lions fail to catch their prey 95% of the time and often go hungry. Male mammals don't get to have sex unless they fight their way up the status hierarchy, and female mammals are dominated by older females their whole lives. Of course animals don't conceptualize their stress, or project it into the future. They release it in the moment. But the next moment they confront a new stressor. They never give up, however. They just keep trying.
As long as you keep trying, your cortisol doesn't get the better of you. You evolved for action.
A lot of times we hear about "living in the moment" and many write it off as some kind of new ageism (or whatever) but here it is, the science. It is our ability to project our fears to the future that do the most damage to us.
Humans have one kind of stress that animals don't have: awareness of our own mortality. Your brain reacts to this awareness as if it were a clear and present danger. Animals don't have enough neurons to terrify themselves with their own mental constructions. You can't escape from the knowledge that the world will spin merrily along without you some day. The thought triggers so much anxiety that people try to avoid it. They project the anxiety onto other things, like health care and finances. No amount of health care and finances will keep you alive forever, so you are better off accepting the fact that you are a vulnerable bit of protoplasm.
I've read this before in other venues and it is true. We set ourselves up failure mentally by creating anxiety about the future (near or long term). It is this fear that stops us from reaching our potential. It is our fixation on "the enemy" that also causes stress. There are a lot of people who assume that because I am "pro-black" that I spend my time worrying and thinking about what white people are doing, saying or have done or have said. I can honestly say that I don't spend the majority of my time thinking about them because I understand that which we focus on is that which we gravitate to. Better to think on and focus on where I wish to be, who I wish to be and the situation I want to have created, than to focus on those who I deem are stopping me from reaching these things.