I believe that positive thinking in the form of neglecting a problem is a losing strategy. A problem is a problem, whether you choose to acknowledge it, or not. Therefore a winning strategy would be to acknowledge, understand and asses your baseline as realistically as possible. Figure out the bad and the good in a situation and operate from there.
By understanding the negative in a situation, which is most usually in the past, you leave room for the solution discovery process, which takes place in the present and then for the positive resolution which takes place in the future.
We’re accustomed to viewing this as “Hope for the best…”, but I’d say “Hope for the best and expect nothing”.
This gives a framework for living actively and happily in the present moment with a positive and optimistic outlook on what’s to come.