A friend of mine had made a recommendation to try to take a positive outlook on life's challenging situations. Rather than thinking negative about how something might turn out, try to take a positive hopeful outlook. While I believe it is better to be an optimist than a pessimist, I think there is an inherent problem in either approach.
The Zen approach to such a situation is to not have either thought - positive or negative. You can't know what the situation really is until you encounter it, so there is no sense trying to imagine it one way or the other. Doing so just creates false expectations and with false expectations comes disappointment when things don't end up matching those expectations. Also, if you start acting on these false impressions or hopes, you aren't living in reality. You are instead letting yourself be controlled by these imagined feelings which may not even be based on the reality of the situation. So, instead it is better to just try to remove all filters and interpretations of what might be and try to get to the root of the present moment, whereever you might be, and experience "what is". Pay attention to your senses, notice things around you that you might not have been aware of before - experience reality. As Buddha said, "The secret of health for both mind and body is not to mourn for the past, nor to worry about the future, but to live the present moment wisely and earnestly."
Of course, putting that into practice on a daily basis is a bit difficult at times, which I think is where the Zen meditation helps. Just sitting, trying to not cling to any thought, really helps condition me for applying the same principles to daily life. Unfortunately, it's something I've haven't been taking the time to do at home on my own. I really enjoy the Zen class at the dojo, but it is only two times a month, and the last class was several weeks ago. Today I have started trying to have a regular schedule of practicing Zen meditation at home, rather than just practicing karate. Hopefully I'll be able to make the time to stick with it every day.