You may not like what is happening in the world or in your life, but if you battle against something you can't change, the result is more pain and suffering.
When you accept what you cannot change you unleash the power to find a different path. What is present will not go away. You can only find a way to cope with it, adjust to it, or find a way around it.
If you battle against what you can't change, you use up valuable energy you could spend on a new path or solution to what is happening in your life.