If control was illusion all along then what are you talking about, going into illusion that you don't have control?
It is not that you don't have a control , but that your control in certain areas is very limited.
Happiness by science standards is chemical reaction in brain, why exactly our actions can cause certain chemicals to form is a mystery , but what is not mystery is that most of your actions , feelings are determined by your habits, habits of thinking certain way, acting certain way, such habits are not easy to break in long term without rewriting them with repetition.
What you must understand is that in a sense there is nothing logical about most of stuff we think, do, I guess for some of us it is even common to know that way we act does not make sense, or rather we don't know why we do it, or question of sense no sense will not even arise, in your case you can start to think that you don't have a control, because you already convinced yourself with some logic of there being no control.
In truth, you can make any truth!