Suppose someone feels jealous over something, and wants to make himself not be envious. What can he do to help himself? I am interested both in classical sources as well as anecdotal advice.
Related: How can I curb my sexual desire?
Well the classic approach from the Rishonim, see Ibn Ezra on Yisro 20 14, is to view the situation like a peasant who sees a princess. He is not desirous of getting her, being that he has no chance. So too are all belongings of another person when we realize who allocated all things to all people.
This seems to be built around the idea presented in Rambam and other Rishonim, quoted in Chinuch #38, that one does not transgress Chimud until they take an action to acquire the item in question, and at the time of ascertaining the item, he has retroactively transgressed Chimud. The appreciation of an item is not what is outlawed, contrary to popular belief, it is the obsession and contrived actions taken to procure it that defines the lav. Whether the obsessed chooses to steal the item or pressure the owner with money in a fair sale.
Personally, I have a similar idea to the Ibn Ezra which seems to find favor in the ears of us westernized narcissists. Imagine Hashem shows you the most wonderful (fill in the blank). He gives you the opportunity to bestow this (fill in the blank) to whomever you wish. The one caveat is it can't be you:) Now, after you present this gift of (fill in the blank) to whomever, would you turn around and be jealous of it? Seems whoever I mention this scenario to says no. The entire reason we are jealous, even while believing that everything is from Hashem, is because deep down we still think well why didn't He give it to me?! But when we find a way to take this anti-Godly thought out of our system, the battle is half won. The Ibn Ezra has his approach to combat this thought process with a mashal, I'm simply adding mine.
Pirkei Avot 2:12:
רַבִּי יוֹסֵי אוֹמֵר, יְהִי מָמוֹן חֲבֵרָךְ חָבִיב עָלֶיךָ כְּשֶׁלָּךְ.
Rabbi Yosei says: The property of your friend should be as precious to you as your own.
I think that the above adage stands on its own merit, and doesn't necessitate further explanation. However, I will add my own take, somewhat.
The above is somewhat of an extension of "Love to your friend as you love yourself." Think this through, a bit. The Torah mitzvah sets yourself as the basis of love. Is this selfish? Not at all! The idea is that normal thinking people (i.e. - no mental problems that are self-destructive, depressive, etc.) always seek the best for themselves. The mitzvah says, that's what you need to do to your friend - seek the same standard of "best" for them that you want for yourself.
Avot narrows this down, here. Just as you consider your own property "precious" - i.e. - you don't want anyone touching, abusing or stealing your property, because, after all, it's yours, don't look after your friend's property - i.e. - don't envy what's not yours in the same way that you don't want your friend to envy your property.
The Torah commands us not to envy. How can we be expected to curb a natural emotion?
Since you asked for anecdotal advice, I will provide mine, which is liberally mixed with (unfortunately unsourced) concepts gleaned from various shiurim, including many of Rabbi Shafier's of theshmuz.com.
The first step is the recognition that if I exist, it's because Hashem wants me to exist. That Hashem created a world with me in it means that I have an important role to play - Bishvili Nivra Ha'olam. But I am not an end to myself. Hashem placed me here for both my development as an individual AND for my ability to connect and change the world around me. My job is to be the soil from which a better family, community, society and world draws its nourishment. And everyone else also has this charge.
Rashi on parshas Vayera notes an interesting dichotomy - Avraham addresses the three visitors in a very respectful, but ultimately human manner. Lot goes out of his way to shower them with words of trepidation, treating them as the emissaries of Hashem that they were. Rashi notes that Lot had seen angels previous in the house of Avraham (and hence recognized them for what they were), but that Avraham's greatness was such that the angels appeared merely to be people to him.
But the critical point is as follows: the greatness of Avraham isn't that he perceived angels as people, but that he looked at people and perceived them as angels. Avraham understood that one needn't be a divine being to be a malach, and that each person (as well as every situation) we interact with in this world shapes and is shaped by us in turn. It is our job to see beyond the surface, deeper than our immediate reactions, to the opportunity beneath.
So how does this relate to your question?
A doctor, a shokhet and a chef all have knives, but it would be foolish for them to covet the tools of the other professions - they aren't properly suited for their employment! A sledge hammer doesn't do the job of a wooden mallet. And coveting the dentist's drill just because it's expensive doesn't make sense when you're job is building a house. If we really, genuinely believe that Hashem is controlling the world, then that means that each person has their role, and that each person is given the tools for their unique role.
At a wedding, we recite in one of the sheva brachot: "Same'ach Tisamach ... kisameichacha yetzircha bigan eiden mikedem." What was the uniqueness of the simcha of Gan Eiden? Adam HaRishon knew, without any question, that Chavah was the only one for him (Rashi - "Zos Hapa'am"). The bracha we wish upon the chassan and kallah is that they recognize that this is the woman, that Hashem placed them here, and that it is their job to recognize the uniqueness of their relationship.
The challenge of envy is keeping this principle in mind for all things (the first clause of Lo Sachmod is eishes rei'echa) - Hashem has set the world up so I am given the tools for my success, and other people's possession aren't worth coveting because their job is unique and different from mine.
Short and (hopefully) sweet:
Just be content and grateful for who you are and what you already have.