God, grant me the serenity to accept the things I cannot change, courage to change the things I can, and wisdom to know the difference.
The serenity prayer is something that has always stuck with me, even with my secular outlook on life. Whether you deem your deity as someone, something, everything, nothing, or anything in between, it gives you some serious perspective around what it means to be happy.
One of my favorite things about it is that it echoes so much of what I've seen in other faiths. Happiness so often comes easily when I learn to detach from the things that don't matter, to take action on the things that do, and choose not to dwell too much over what little control I have over the rest of it. The secret is accept it, fix it, or let it go, and for the most part, I get to determine what matters. I can always change my mind.
One thing I've been working on changing my mind about is phone calls. I still get butterflies when I pick up the phone to call someone, anyone. I have pretty negative associations with phone calls now. The usually come bearing bad news. So I'm trying to change that mindset by choosing to call people when things are well, not when there's a problem. Seems to be working well for me, to take control when I can, rather than passively assuming I'm bothering folks, or that they don't want to talk to me.