I am scheduled to give a talk next semester on ideas related to happiness. The book by Dan Gilbert, professor of psychology at Harvard, called "Stumbling on Happiness" is about difficulties people have at getting happy. He discusses research that shows that people are often poor at estimating what will make them happy, how happy an event will make them happy and how long that happiness will last.
We are probably all familiar with the law of diminishing returns. It is not really a law but more like a common pattern that you can expect to see in many things. The first bite of a wonderful cherry pie is more than wonderful, the second bite is good but not quite so stunning, the third bite is very good but by now, we are getting used to the taste and by the end of the serving, we are more comfortable refusing a 2nd piece than accepting one. The Buddha wanted to get clear about happiness and living a life and about 2500 years ago, said that you can rely on change in this human life.
The wonderful pie changes from being eaten and the wonderful taste becomes something we get used to. A wrinkle I just ran into is that the normal human perception of the time we are transfixed by the wonderful taste usually seems shorter than the miserable time we have eating a broccoli and eggplant overcooked pie. So, delight seems shorter than misery.
It is true, of course, that change is always with us, including change out of misery toward happiness. Yucky stuff passes, too.
There are three TED talks by Dan Gilbert
https://www.ted.com/search?q=Dan+Gilbert
He is quoted:
"Human beings are works in progress that mistakenly think they're finished." Dan Gilbert shares recent research on a phenomenon he calls the "end of history illusion," where we somehow imagine that the person we are right now is the person we'll be for the rest of time. Hint: that's not the case.
At an older age, it might be a little easier to see that one changes all the time. And, of course, so does everything and everyone else. We don't want to let that fact paralyze us, nor panic us. We will just continue to do what we can.