I have been making happiness my default feeling for the past year and I can promise you that it is not mundane and it has only enriched my life. Life is better when you Feel Happiness
Maybe you'll have to define it better. I think thankfulness, contentedness etc. are precursors to occasional happy moments. You can still be sad/disappointed but choose to be thankful.
Being sad/disappointed can happen but holding onto that feeling is where the problems occur. Being thankful/content can happen and holding onto that is where happiness occurs.