Idiom
make up mindmake up (your) mind
1.
to decide what to choose.
I can't make up my mind whether to have the salmon or the chicken.
(often + question word)
2.
to become very certain that you want to do something.
At a very early age she made up her mind to become an actress.
(often + to do something)
My mind's made up. I'm handing in my resignation tomorrow.