WHY IS IT THAT HAPPINESS DOES'NT LAST? SEE WHAT I MEAN: I WAS THE HAPPIEST PERSON ON EARTH THE DAY I PASSED JAMB, I WAS THE HAPPIEST PERSON THE DAY I GRADUATED, I WAS THE HAPPIEST PERSON THE DAY I BOUGHT CAR AND ON AND ON AND ON BUT I DISCOVER THAT I TRY HARD TO HAVE THAT LEVEL OF EXCITEMENT I HAD WHEN... BUT IT JUST CAN'T BE UPTO EVEN HALF OF WHAT IT WAS WHEN THAT PARTICULAR EVENT TOOK PLACE AND WORSE MORE IS THAT I WON'T EVEN FEEL ANYTHING IF I DON'T PUT MY MIND ON THAT PARTICULAR EVENT. DOES ANY PERSON HAVE THIS SIMILAR EXPERIENCE, HOW DO YOU RETAIN YOUR HAPPINESS OVER A LONG TIME

It's called the Hedonistic Treadmill
The hedonic treadmill , also known as hedonic adaptation , is the observed tendency of humans to quickly return to a relatively stable level of happiness despite major positive or negative events or life changes.


Also when you are happy (read: feeling pleasure) your brain secretes Dopamine a neurotransmitter with a short half-life, with means the effects fade sooner.