I certainly know that the Serenity Prayer is about acceptance. For me, it is about knowing the difference about what I can change or what I can't. I find that I could have made it much easier on myself by quitting the debating society.
Have to accept where they are at in their program. As my sponsor use to say to me, be grateful that you aren't in the same place. There is always someone who 'knows' how it is done. I may know something but in the moment, it flies out the window and comes back later to bite me in the butt and I think, now why didn't I do that before.
Accepting ourselves and others is not easy. We can say the words but it is an altogether different thing when it comes to feeling it. Even more difficult to let it go.