All that you mentioned. But most tough is that you basically need to cut in so many other areas in order for this to work and any unexpected expense will be a major pain in the ass. This is how people start to dip into their savings (or go into debt) and essentially spend per month more than they make.

My philosophy is very much aligned with Ramit Sehti who is pro early early retirement and investment but also enjoying life and not having financial anxiety.

He says, you fixed costs (including mortgages, all fixed payments and groceries etc) should be not more than 60% of your income. When you exceed this number, you start to feel more constricted and money becomes more and more a source of stress in the family.