Trying to stay positive when bad things happen may backfire because usually it involves resisting any bad feelings you may feel and repress them, which will not do you any good and it may end up making things worse. In my experience, the most effective way to deal with bad moments is allowing yourself to fully feel whatever you may feel. Some time later, you may assess the situation. No situation is completely and utterly negative; the proverbial "half empty glass" vs "half full glass" is applicable. Once you are feeling better, it may be time to leave it in the past and look for the positive within the negative.