This is exactly what I do with gambling- I go out with a set amount of money and nothing else, so I can't possibly spend too much. I have good self-control besides that, and I've never gambled more than I could ever afford to lose.

The subreddits Fatanut listed are good, and I've personally browsed the latter one (r/getdisciplined), but if you're having a hard time reading the articles, there is an option to switch to old Reddit in the top right. Nobody I know likes the new interface as it's slightly more difficult to skim and read, and it's also slightly more demanding on your CPU than the old interface.