“You can’t make a silk purse out of a sow’s ear”, as the famous adage goes. Your raw materials define what is possible with them.
The same is true of your mental life: you cannot make a good life out of bad imaginings.
Your mind is a scrapbook. Like any scrapbook, it collects fragmentary images of whatever you decide to put in there. Over time you fill it up. And eventually, what you have put into it defines the kind of life you’re going to have. That happens because the ‘resources’ you put into your mental scrapbook become the raw materials for your present attitudes, your frame of reference for present experiences, and the repository of images for your present imagination.
Garbage in, garbage out. Good stuff in, good stuff out. It’s that simple.