Time is money and our weaknesses in dealing correctly with time are similar to those involving money. Some people simply can't make it on time. They arrive late to meetings and appointments, they wait for the first piece of a concert to finish before they are allowed into the hall, they make their date wait 20 min alone at a table before they show up to dinner. Often such behavior is interpreted as arrogance and self-importance, which is why it entails a severe social price, but in most cases it is simply a result of bad management and a problem of self-control. People who are aware of their problematic relationship with time use tricks to do better. A quite effective one is to set your watch 10 min ahead. The feeling of being late often helps us to hurry up and put aside distractions. Overspending money is a quite similar habit. Budget is a schedule and living beyond our budget is not much different from running behind our schedule. Being late to an appointment means that we have consumed time in an inappropriate way – either by letting temptation lead us to do things off our planned schedule or by miscalculating our time budget.
Overspending is likewise driven by temptation (to consume beyond our means) or by miscalculation (of our financial abilities). This means that setting up our "money watch" to run $x earlier might help us to deal with overspending. You can simply create a second, virtual, bank acount that will constantly show, say, $1000 less in its balance (compared with your true one). This will make you more alert to a potential overdraft earlier than usual and may make you think twice about your next purchase. If you end up spending less and realize a positive balance at the end of the month, don't roll it over to your next month's budget. Put it aside in a savings account and reset your money watch to run a few dollars ahead.
Keep doing this until you feel you manage to come to terms with overspending or until you become rich enough so that it doesn't really matter.