You don't need 'The Serenity Prayer' if you always have things your way. When you cannot change people or circumstances (Box 1) you need wisdom (Box 2) to handle the situation. Wisdom develops from learning from experience from such situations which you were powerless to change, which you might now succeed (Box 3).

Box 1 often brings Box 4, i.e., hardship may be even suffering. If you can have Box 3, the hardship (Box 4) would be reduced. But Box 4 also helps to develop serenity (Box 5) and with time faith in God (Box 6). Faith leads to courage (Box 7) producing wisdom (Box 2).

Serenity, faith, courage and wisdom cannot be got if in one's life if "Cannot Change" (Box 1) never happen. Life needs a combination of Box 1 and Box 3. Hence , "to accept the things I cannot change; courage to change the things I can;and wisdom to know the difference"