The way I "managed" it long-term was by creating a spreadsheet of all of the things I really want (like, spent years wanting) and their costs, adding them up, buffering it a little and saying "that's my target number, and I'm sticking to it." Last time I did this, I calculated that $5M is my number. This would generate about $200k/year with 4% return and withdrawal rate. Everything I do in my career is centered around getting to this number before I'm 45, so that I can decide whether I want to retire or not then. (I probably won't, but life isn't static.)

The way I manage it in the short-term is the two-week test. If I want a thing, and that thing is >10% of my remaining disposable income (which I budget every two weeks), I tell myself "if I still want this in two weeks, I will buy it or start saving for it then."

Example: I really wanted the custom truly-wireless IEMs that Bragi makes. However, they are $599; not a cheap purchase at about 50% my two-week disposable. Instead of buying them outright (I could, but that would affect disposable income for going out and stuff), I sat on it for several months while I tried other headphones. The urge to get them didn't go away, so I got them. What would have been an impulse purchase became a planned and extremely-worthwhile purchase.

My self-control isn't bulletproof, however. Our five-year old vacuum stopped working the other day. I tried repairing it several times, all to no avail. I got tired of having dirty carpet (our apartment is all carpet except for wet areas), so I went to Best Buy and got a new one. While I was there, I saw a Bissell Carpet Cleaner that looked really useful, as our carpets haven't been cleaned since we moved in three years ago. Both combined were about $500, but I impulse-bought it because dirty flooring drives me nuts. While I'm really happy with this purchase (there are few things more satisfying than seeing all of the gunk in your carpet vacuumed up), it was definitely impulsive, and my more responsible self should have waited on it.

Aren’t those carpet cleaner rentals only $30 for 24-hours and at most home centers and grocers? I get wanting to have clean carpets, but I’d much rather rent and not have to deal with storing the thing, let alone buying it.

This machine works better than carpet cleaner rentals, can be used whenever I want (I used it this morning to quickly pick up cat vomit residue :( ) and I can install a tool that allows it to work on bare floors

I haven't solved this for video games, youtube, etc. I'd be interested in a solution!

For disposable income purchases, we budgeted out income, necessary expenses, savings, travel, etc., everything that requires long-term planning. The surplus (a fairly small portion) we then divided out into a per-person, per-day allowance.

I use a simple Google Form to record discretionary purchases, tracking the results in a Sheet, to account for whether this discretionary budget has a positive balance.

This has the nice effect of translating dollar values into time values, and giving a reference point for trading off the relative hedonic value of small frequent purchases vs. large infrequent purchases.

You may want to look into how to use hardware to implement a sort of Ulysses pact - depending on the nature of the behavior(s) that you want to control, a time-locking safe can work wonders.