It is what it is
Once you realise “It is what it is” you also realise what can and can not be controlled. This is powerful and will allow you to move past the things we cannot control and come to terms with the events in life that we can only control by the way we think and react to them.
What can you change your thinking about?
I am not saying to just give up on changing everything in life because there are things we can and should change and can control.
What I am asking is for you to consider all the things that you give energy to worrying about that you can not change. Things in the past, things that may or may not happen, things that someone else is doing.
These are areas where you can focus your energy on momentarily to acknowledge a reaction and then let it go from your thoughts. It is what it is.
As an exercise you can write a list of all the things that bother you and then work out from that list how many you can actually control.