But your own mind is not completely within your own control, I would argue.
Free Will doesn't really enter into this, so we don't have to enter that rabbit hole.
The true nature of free will and its connection to determinism simply isn't relevant to whether desires are causally connected to outcomes, and so whether this belief is well founded.
Edit: the only way out of this is to be a fatalist, whereby outcomes will always happen no matter how hard you struggle against them, that they are independent of our desires. Few people subscribe to such a view though, and if you happen to, then I can only say I'm sorry.