You are not your thoughts in that thoughts come to you without you getting a say in it.
You may get control how it affect you like you can direct the flow of water. But you don't get to decide if the water comes at you.
You get to direct (not control) what thoughts come to you by curating your info diet. But even that is cyclical; it's a function of what and who you've already exposed yourself to. In that sense even your level of agency is partial at best.
Side note: unthoughts are exponentially more out of reach.
If you accept this premise and thoughts are treated as external entities, the good news it means they are something you can sculpture and shaped into something that serves you.
What does sculpturing thought mean? By having it be the subject of your curiosity, and if appropriate have it turned into action.
How do you do that? You need to be able to observe the thought without participating in it. Let it flow where it wants to.
If the thought feels angry, you are not angry, the thought is. Don't let it get you angry, but don't try to stop the angry thought either. Ask why it is angry, why it this useful, how can you opportune this.