You change your mindset by acknowledging that you are wealthy in things that matter. You see, beyond food, roof over your head and various practical needs, money is merely a means for achieving certain feeling-states, often fairly fleeting.
You get a certain watch, car, apartment, vacation as they make you feel a certain way. You see, things in themselves have no value beyond what we give them. If it wasn’t so, everyone would feel the same towards a Ferrari, Oysters or a vacation in Paris. But we don’t, far from it. Now, you better ask yourself if there isn’t other, more accessible routes to achieve these states of feeling without having to acquire all these things. And there is.
One of these ways is to practice gratitude in the sense that you list and connect with a sense of love and gratitude towards various things in your life. Noticing the blessings you already have attracts the feeling of wealth you are looking for, and the best thing, it’s all for free. : )