It is certainly not always easy to be that happy go lucky figure all the time. In fact it would not be normal to only experience feelings related to the positive side of life; after all how would we know what is positive if we did not know of anything negative. However, it is important to try and draw positivity out of any situation despite how negative the experience may be as a whole. Food poisoning from a restaurant? Well you will not be going back to that establishment and thus are preventing another instance of that from occurring in the future. A breakup with a significant other? First off nothing is ever set in stone when it comes to relationships, but chances are you did learn a great deal about what you need/want/will give in the next relationship to make it more successful. Loss of money? Chances are you will be able to recognize and avoid the situation which caused the loss and thus prevent a future loss from occurring in the same way. It is all essentially about growing from experience and allowing mistakes (or the negative) to lead us to an ultimately higher quality of life. If you can take away one positive point from every negative experience then you not only grew but also increased your level of attractiveness.
It is not about running around with a permanent smile tattooed to your face but more so understanding that if it didn’t kill you then you survived and that in itself is something positive.