On your own terms.
Can I say 'vivir en sus propios términos' for 'live on your own terms'?
2 Answers
I think you are better off saying 'vivir por tu/su propia cuenta," literally 'of your own accord.' You might want a native speaker to share their ideas.
Here's another one:
salirse con la suya = to have one's way
Me da asco que mi hermana siempre se salga con la suya.
It disgusts me that my sister always gets her way.
We could also say:
Vivir independientemente (hard to pronounce, right?) = to live independently
No tener un pelo de tonto = to be nobody's fool