You have a long lineage. 
Your ancestors were quite primitive. 
They followed their instincts. 
The fight or flight syndrome, linked to the limbic system of the brain,
ensured greater survival.  That part of
your human brain still exists and operates in you, but it need not rule
you.  When the alarm goes off in your
head and says, “Run or fight!” you now have a part of the brain that can
reason.  In that brief moment before you
act, shift gears and reason with that neo-cortex—the newer, more advanced part
of the brain.  And then, if you have
reasoned that there is no immediate threat to your physical existence, shift
gears again.  This time, use the part of
you that is far more advanced than the brain—the part that existed before the
brain and will exist long after the brain no longer functions:  the spirit. 
If there is truly no reason to fight or flee, then the choice is quite
easy:  love.