I want to have a home of my own, but I don't have one. This feeling makes me sad. Why? Secondly, there is some fancy chocolate in the house and I often like to have a piece. Wanting this makes me happy, even though, like a home, I haven't obtained it.
A Buddhist might argue that desire itself causes sadness, yet in my desire for chocolate, with the knowledge that I can have it, made me happy. Anyone who has fed an expectant pet, or seen a child on Christmas Eve, keen to obtain an anticipated present the following day has seen that desires can create happiness. One could argue that this desire is avaricious (a word rich with the emotive language of religion and sin!), but no matter what, this feeling is clearly positive, even in the dog!
Desire, perception of want, is fundamental to happiness and sadness. The important thing is whether you believe you can get what you want. A hungry man on the street, penniless and staring in through the window at a restaurant might be sad. A hungry man in the same circumstances, but with money and staring through the window in anticipation of going in and eating might be happy. The circumstances are the same, except for the expectation.
To want something and expect to get it then can make us happy, and to want something and not expect it can make us sad. What if this expectation was unreasonable, such as expecting to win a lottery jackpot next week? This expectation can make us happy, until the draw occurs and our hopes are dashed. That event would plunge us into sadness because we would have misinterpreted reality. We would be forced to accept that our expectations were false, and that next time, we should not expect such things, even though that expectation made us happy for an entire week.
In those circumstances, the loss of facing reality should feel more painful than the pleasure of the expectation. If it were otherwise, we wouldn't have any motivation to learn or to face reality, we could happily remain delusional for our entire lives, but almost certainly to their detriment. The starving man wouldn't need to look for food, because he'd expect it no matter what, and without looking for food, he would eventually starve.
(This is an unrealistic scenario though, as in a life or death circumstance such as starvation, the man's body would tell him quite firmly that he'd better go out and look for food, thus forcing a "reality check" on his delusion. Perhaps the same is true of love, so it's not quite yet proven that heartbreak must feel worse than love feels good!)
So reality is important, and so perhaps the best expectations should be realistic ones. But, what if we could expect something good that could not possibly be disproved, what then? What if we were to expect something amazing to happen to us after our deaths, eternal fame as experienced by Vincent van Gogh, or eternal joy in heaven? As this expectation couldn't be disproved, it would have the capacity to make us happy for the entirety of our lives, making us feel better without the possibility of facing reality. Nobody could ever prove to us anything about a future beyond our lives. So, are delusions of this sort are universally beneficial? If so, why doesn't everyone have them? Many religious beliefs are centered around what might happen after death, so perhaps this is why. There is at least one downside to these delusions, that nonsensical beliefs that cannot ever be proven or disproven start to spread and affect society as a whole in a harmful way.
In the real world, however, there are more than definite possibilities and definite impossibilities, in fact most things that we might want are possible to some extent, merely varying in likelihood. The lottery win may have been possible theoretically, after all, but other things such as wealth, a sunny day tomorrow, popularity among friends; the possibility of these wants can be difficult to assess, yet the belief in them is vital to happiness. Because of this, confidence in our ability to obtain our wants is linked to happiness.
If you confidently believe that you will eat in that fancy restaurant, and can achieve that goal, then you will become happier. If you don't expect that you will eat there, you will become sadder. The only difference is your perception of the likelihood of achieving your desires, which can continue until the desire is definitively met, or definitively not met; an outcome which might have a time limit, or may not, depending on the nature of the desire.
So, if this is all true, then an instant way to become happier is to believe that you will get something, a reward, but, if this is unlikely, you must ensure that there is no time limit to your desire. Truly believing that you will one day own a huge mansion would make you happier, providing you don't mind waiting forever for it. Truly believing that you will achieve some great "Vincent van Gogh-ian" success after your death would make you happier. These beliefs can not be proven to be impossible, and so your desires for these positive outcomes will never be truly unrealised or quashed by mere reality.
There is a final amusing twist to this, because once you achieve a desire, the happiness that desire created vanishes. If you wanted money, and knew you could have it, that expectation would make you happier than actually obtaining the money. This is logical because life and experience is about moving toward something, gaining, not standing still, not owning.
Money, in this example, might increase happiness indirectly though, by making it easier to obtain other things. Money has that property. It makes it easier to gain other things, but remember, it's not gaining things that creates happiness, it's the belief that you can do so. So perhaps, being confident that you can make money if needed, and being confident that you can make friends if needed, and being confident that you can get any resources you need, if you really needed them, is best of all.
