You can change your reality anytime you want. It is true! Everything is mental meaning what you think in your head is real to you. If you don't like your reality change what you are thinking about. You can change your mood, which is only a mental state, by using your will and effort by fixing your attention on the changes that you want to have in your life. If you have some kind of belief that is holding you back get rid of it.
In fact examine all of your beliefs and if any are limiting you and your life change them by replacing them with a new belief. All that is required to change a belief is to changing your mind. If the old belief comes up again keep replacing it with the new one till the old one doesn't surface again. It is time to clean out the old and bring in the new so we can move forward!
You ARE the creator of your life!