A throwaway article in a "throwaway" journal (Psychiatric Times) sums up the worldview of the famed cognitive therapist Albert Ellis as follows: if you're unhappy about your situation, change it; if it is beyond your ability to change, accept it because it is reality. Why is this so hard to do? If the Serenity Prayer were ever conclusively answered, people like me would be out of work.
Life is hard because none of us ever really attains the wisdom of the Serenity Prayer (i.e. to know the difference between what is in our power to change and what isn't). Sure, we know we're never individually going to modify the constellations or even affect climate change in a major way, but when it comes to a host of more modest life situations, we grow frustrated because we feel that there must be a way to effect change if only we achieve sufficient persistence or ingenuity. Most of us err on the side of passivity or of futility--to get it right would be to live on a tightrope. To what extent do we actually exert control over our lives? Time will tell.