It isn't human nature to be contented.
After all, pleasure doesn't exist for its own sake. It exists to drive us toward those things that are good for us -- whether food or water or companionship. We know those things will be pleasing, so we seek them out. But our brains can drive us just as efficiently with the desire for them, as with the pleasure of attaining them. Or they can simply make us uncomfortable with the lack of them.
But even when you attain it, pleasure is always fleeting. When you come in from the cold, sitting by the fire is wonderful, but after a few minutes you no longer notice it, and a few minutes after that, you're too hot and have to move. Eating is fun, but you can't spend your whole life eating. You can spend hours being hungry, preparing a nice dinner, and it doesn't take you more than half an hour to eat it. Enjoyment is always more intense when it's a big change from something unpleasant -- eating when you're starving, coming inside when you're cold -- and without some amount of suffering to mix it up, you're not capable of enjoying anything very much.
Because we're constantly rushing through time, unable to slow it down, tiny moments of beauty and joy flash by before you can really appreciate them. You can spend all year saving for a vacation, but the vacation's over in two weeks. Just surviving takes a lot of your effort -- at least eight hours a day for most of us, even in this decadent modern age.
And at almost every moment we are alive, we want something that we don't currently have. It's the nature of being human, to always want to stretch for something further than we possess. We wouldn't achieve very much without this drive. But at the same time, it spoils many moments that would otherwise be very pleasant. The person who makes $20,000 a year feels he'd be perfectly happy if he only made $30,000, but when he finally reaches his goal, he thinks surely he'd be happier if he made $40,000. We often put off our happiness for some later date when we have what we want, but there's always something we want.
I'm not saying all this to be depressing. Life is mostly not too bad. But it's unsatisfactory, which is why we all dream of a second life where we could actually be satisfied.
I deal with this basic unsatisfactoriness in two ways. First, I set my goals on things that don't fade. Pleasure is the briefest of all possible goals to strive for -- you could spend your life chasing it and still be without it most of the time. So I don't spend much effort on that. But the satisfaction of a job well done lasts a good bit longer. The knowledge that you love and are loved, that is something you can keep with you all the time. And making an actual contribution to the lives of others is the longest-lived of all -- because it can last even longer than I will. My whole life, it will never cease to be true that I brought three beautiful humans into the world and gave them all the love I could. And I imagine it will always be a comfort to me to remember that.
The second way is just gratitude. I refuse to delay happiness to some later date -- I will look around at the happiness that is already here and make a point to enjoy it and feel grateful for it. It makes me sad that a flaming red leaf has to fall from the tree so very soon. But it's less of a tragedy if I actually saw it and appreciated it before it fell. Sometimes I get caught up in the things that I fear, the things that make me angry, the things that I want, that I can't see the good things around me right now. But when I stop and notice my life -- full of small good things, free from want, overflowing with love -- I can't help but be happy.
Life may be unsatisfactory -- perhaps it was meant to be -- but that doesn't mean it can't be good.