Is Resilience The Key to Happiness?

According to an article posted on the BBC, the key to solving depression and finding long lasting happiness might lay in a person’s capacity for resilience. However many questions remain about resilience – is it learned, is it something you are born with or is it within your brain chemistry?  I wonder, once you develop it, is it something that works for all situations and circumstances or are there different strains of resiliency one needs to develop to cope with the plethora of situations people face every day?