Assuming what is taking you over budget are not essential costs such as fuel bills, food, mortgage etc. you could do the following. Work out your monthly disposable income after all essential base costs have been sutracted. Then simply keep a book of any additional spending.
It will be very easy to see if you're at risk of overspending. In fact, even when one has no need to budget it's still an excellent idea to keep a book of all your spending. It's surprising how useful it can be. It's a great reference for dues dates, sizes of past bills and provides an excellent cross check of your bank statement.
It's not often that you find an error on your bank statement (at least it shouldn't be!), but my books have helped me locate three such errors over the past 25 years, which I'm sure would have gone unnoticed by most people.
So my advice is, keep a book of your spending.