A woman I know told me she spent a year (if I remember correctly) telling herself to look for the best in every man she met, and found that many of them became more attractive (as an aside, but not much of one, I've read several times women rate 80% of men as below-average in looks).
What this women proved to herself (and indeed to anyone who pays any attention) is that attraction in some measures voluntarily. I couldn't quite figure out, though, why looking for the best in people makes them more attractive.
Then I realized it had to do with appreciation and gratitude. I have memorized this relevant quote from Meister Eckhart: "If the only prayer you said was 'thank you,' that would be enough."
I think many people these days aren't quite sure what Eckhart's quote means. But if you can real true appreciation and gratitude, it is an amazing thing, and you can't be happy unless you have it. That's why I realized my woman friend was telling herself, "Find something to appreciate in these men." And they suddenly became more attractive, not because they were any different, but because she was different.
In fact, in love there is always appreciation and gratitude. This has been confirmed by researchers. I read an article once that said to maintain a relationship you must: 1) feel gratitude 2) show thanks 3) look for appreciation.
There are some differences between those three things. You can to consciously look for things to appreciate, which is what the woman I know did. Then you have to feel the gratitude. Then you have to show the thanks.
The one thing that is absolutely inimical to to gratitude is envy. It's such as old observation there are Aesop's Fables about it, such as "The Fox and the Grapes," "The Ass and the Charger," and one with the obvious name of "Avaricious and Envious."
The last one I will quote in full because it's such an interesting thought experiment: "Two neighbors came before Jupiter and prayed him to grant their hearts' desire. Now the one was full of avarice, and the other eaten up with envy. So to punish them both, Jupiter granted that each might have whatever he wished for himself, but only on condition that his neighbor had twice as much. The avaricious man prayed to have a room full of gold. No sooner said than done; but all his joy was turned to grief when he found that his neighbor had two rooms full of the precious metal. Then came the turn of the envious man, who could not bear to think that his neighbor had any joy at all. So he prayed that he might have one of his own eyes put out, by which means his companion would become totally blind. "Moral: Vices are their own punishment." In a sentence, envy is so agonizing it is it's own punishment.
Let's put it this way: you can't feel envy and gratitude at the same thing. This is such an important thing researchers have put a lot of effort into studying it. Melanie Klein wrote an important book about it, called, not surprisingly, Envy and Gratitude.
Klein found, and many researchers after her, that babies go through three phases: envy, guilt, reparations, gratitude. I have seen this sequence in novels and movies, such as Dostoevsky’s Crime and Punishment and the Robert DeNiro movie, The Mission.
Think about it this way; until those who envy feel guilty about it, and make reparations, they will never feel gratitude, will never know well-being, will never flourish and never know love and satisfying life.
And the first thing, I'd say, is to look for things to appreciate.