Mentally and emotionally, I live simpler by just asking why this matters so much to me, will it matter still in five minutes? An hour? Tomorrow? Is it worth getting upset over it?
Once one has that down, it's easier to look at objects and say do I need this? Is this of used to me at the moment? Once a day? Once a week? A year?
This is on par to looking at services, except the question is "how does this contribute to my growth or stability?" For example, cable does not. Car insurance does not contribute to either, and thus I have neither car insurance nor cable...nor do I have a car. The bus gets me around just fine, and allows me time to read and unwind from my day. It ensures I walk when buses are not available, and thus I get my exercise in.
At the end of the day, the best question(s) to ask is "How does this contribute to my being?" "Is this a positive or negative experience I need to carry with me?"
Don't be afraid of complicating things too with simplicity. A very basic example would be instead of wasting money on batteries for the remote control, chuck the remote and get up to work the TV manually. Or instead of writing in "leet speak" when writing, write out the whole word, give your hand some exercise.
Don't give into the stress and remove the subtle stresses, such as excess bills that are not essential to existence.