Do you have a default level of happiness?

If happiness really is 50% genetic and 50% external factors as some studies have suggested, and you subscribe to the hedonic treadmill theory, what does this mean for the pursuit of happiness, and what do we make of the 50% over which we have some measure of control?

Based purely on personal experiences and observations, I am inclined to believe that there could be something to the notion of a default level of happiness, based on the combination of a genetic baseline for happiness and a constant re-balancing of our mental and emotional states. Over the years, major isolated events have brought about about spikes and plunges in my moods and feelings, but it does seem that my contentment levels always eventually return to a familiar balance.

Involving oneself in worthwhile activities and goals - what is considered 'worthwhile' is subjective to the individual, of course - should increase levels of happiness beyond what has been given genetically, however if you throw in hedonic adaptation as well, achieving more will not necessarily ensure a substantial difference in your general happiness. Call that the happiness equivalent to lifestyle inflation, if you will.

Now this might all sound a little depressing, but in some ways I actually find it quite comforting, and here's why: extrapolating from the above, happiness may not necessarily be related to how much you can accomplish according to traditional or societal parameters but may, however, be elevated and then maintained through doing what you love - which I consider a success in itself. Now that's something worth feeling happy about!