Painting Dilemma

We have been in this house almost 8 years and some of the walls really need painting.  The problem with painting is that you can never paint just one wall because that one freshly painted wall makes the one next to it look grungy.  It will look grungy and need painting even if it looked perfectly acceptable just before you painted the first wall. So you paint the second wall which makes the next one look forlorn and in need of paint and before you know it you have been sucked into a major painting project.  I've considered just learning to live with it but I know me--I'll decide that it won't be too bad to paint just that one little wall...I'll buy just enough paint for that one little wall...How much time and mess can painting one little wall create...Here we go again...