I'm not sure. We can delay these things in the expectation of future happiness but just as the happiness from sense pleasure doesn't last, I think the same goes for less obvious things. For instance you could spend long, hard periods studying for a qualification. (i.e delayed gratification and making sacrifice) but the 'high' from achieving your qualification will fade away as well, over time.

I'd appreciate if you could put forward your exact view on the subject so we can compare and relate?

I believe that Sense-pleasure and fulfillment are different methods to the same end. Sense-pleasure can lead to a (temporary) sense of well being and fulfillment. For instance, can you not say you feel fulfilled after eating a delicious chocolate cake? Do you not feel your stress melt away while lying down in the sun for half an hour? My point is that you feel peaceful and at ease in the wake of sense pleasure. So pursuing sense pleasure and pursuing fulfillment are just two methods for realizing the same end. The end of relief, peace, fulfillment, ease, well-being. In short, Happiness.

The problem is that, as we've both agreed on, is that sense-pleasure is not sustainable. However, at the same time, it's what we've evolved to do. We've evolved to seek out pleasure at every opportunity. As I said above, this is great for the survival of the species but tragic for the individual.

What Happiness is there in life if we are constantly chasing after more, more and more?

Do you think (honestly) whether we have the option of jumping off the treadmill? refusing to play the game and looking elsewhere for fulfillment? Or do we have to be slaves to our desires for the entirety of our lives?

Thanks for talking to me about this :)

I'll reply to your second point first:

"Is there a choice?"

My answer is: Maybe?
For instance Buddhists believe lasting happiness (i.e. peace) can be attained by letting go of attachment to things. Maybe some form of practice could 'rewire' your brain or prove more fulfilling than chasing things, eternally on the treadmill.

Reply to your first point:

" 'Mechanisms for happiness' is an odd distinction and could probably use clarification."

My working definition is, as stated above, that Happiness is the sense of release and rest achieved by various means. So a mechanism for happiness, is anything that brings about that state of ease. It might be the relief of hunger by eating, for example.

" Is happiness sense pleasure? Is it a sense of well-being or fulfillment?"

That is really making me think. I guess I'd agree with you that it's well-being and fulfillment (I'm assuming that's what you believe???). Sense pleasure provides that - Just only for a short while. Finding lasting, stable well-being and fulfillment without relying on sense-pleasure sounds like a much more realistic thing to achieve...