People often say that the inner workings of the mind are complex. But then people tend to use ‘complex’ to describe things they don’t understand.
In that case, ‘complex’ says more about the person making the doing the describing than it does about the thing being described. Complexity is like beauty; it’s in the eye of the beholder.
In any event, complexity need not be a barrier. We all make regular use of complicated things without understanding how they work, including our minds. We don’t need to understand something in order to make use of it.
Understanding how to use something is usually much simpler than understanding how something works. That goes for our minds too. We shouldn’t be put off learning how to use and control our minds, just because we don’t understand fully how the mind works.