What is the truly revolutionary advance that humans are making in the evolution of life and consciousness on Earth? The ability to live without fear.
Fear, as an emotion, is an effective survival asset for creatures that do not have as much power to change the environment as we do. An instinct to jump away from a sudden stimulus appears in amoebas. In higher mammals, cognitive understanding of the environment allows cautiousness and flight/fight responses to be focused on things more likely to be real threats.
But the emotion of fear has very few positive effects for human beings. How often do we face threats that can be dealt with by the tendencies fear engenders? Only a soldier on a battlefield, or anyone in a dark alley, is more likely to survive is some circumstances if he or she is afraid. And the number of times in which any human being has ever survived because he or she was afraid at a given moment, is so small as to be statistically zero - at least since we stopped being large-animal prey, that might move faster with adrenaline in its bloodstream.
Don't conflate fear with rational understanding of risks. If you are "afraid" you might get killed in an auto wreck, and therefore refuse to ride with a drunk driver, any actual fear you experience is beside the point. You made a rational decision to avoid risk. You didn't need the emotion of fear to compel you to do it.
This is the controversial issue. It is hard to grasp the concept that the actual emotion of fear does not contribute to survival, and therefore does not need to be clung to.
Examples abound of situations in which fear is a detriment to survival, clearly. In all emergency situations, the first and strongest advice is, "Stay calm." But in the 99%+ of our lives that are not emergency situations, we often make no effort to stay calm. Some of us let fear completely control us much of the time. Is there a reason to think that allowing fear to rampage when we are _not_ in an emergency situation is any better for us than staying calm? I am speaking as a sufferer of anxiety and and panic attacks. Trust me, I have experienced fear in the whole gamut of situations, and in none does it do any good. (However, I have not been in a situation where I could hope to outrun an attacker. Such an attacker would have to have a limp.)
Adrenaline can make you work faster as well as run faster. If your survival depends on building a sandbag embankment before a storm come, fear could be helpful. If you are the engineer designing the embankment, too much fear will reduce your community's and your own prospects.
I believe that there is no downside to releasing fear. If fear is appropriate to the situation, it will be helping you do your work faster, but you won't be aware of it. If you are aware of it, it has already gone too far. You need to be using those brain cells to figure out what to do. Every thought cycle that involves fear is wasted.
I believe that my lassitude, and the tendency of most people to sit and do nothing, come from the fact that our brains are soaked in fear. If yours is not, congratulations. But if the shoe fits, wear it.