It is true that if you intentionally project positive energy, it can go far to balance out challenging circumstances. Some of us know this, some of us forget this. How do you regain it? It begins with internal stubborn attention to positive energy. Project it nevertheless if that is your genuine and authentic intent. In many cases, it can help define circumstances in a more positive way.
Does a positive frame of mind mean that you ignore reality or ignore disappointing things? It does not have to mean that at all. Simply that you do fully see the downsides and you are simply committed to move past them because with enough persistence you can. You nor I always have the answers, and sometimes pain, trial, and unflattering times are unavoidable. Remain strong, humble, and faithful. It is at those times we can recover our overall disposition to say, it is going to be good anyway both with our actions and our faith.