For the past three years, I've been living an experimental lifestyle. I've kept so few possessions that I could carry everything I owned with me. I took it to extremes at times. I think at one point I had about 5kg of things. It's been an eye-opening ride, and will affect how I live forever.
My motivation was exactly the same one that's caused thousands of men for thousands of years to abandon possessions. Greek philosophers, Hindu ascetics, Siddharta Gautama: they all knew that possessions come and go, and can be taken away from you through no fault of your own.
I see people depending on their possessions all the time – not just people, I see entire civilizations depending on their possessions. If you lean on your possessions, then when Fate kicks them out from under you you'll fall on your goddamn face. If you hold them lightly, then the thieves, fire, or repo men can come and take them, and you'll still be standing. Most of my few possessions were destroyed in a fire in 2015, and I barely cared at all. If possessions aren't making you happy, losing them can't make you upset. It is far more intelligent to base your happiness on things you can control, like your attitude.
These are not new ideas. They're all laid out by Epictetus, Seneca, and others. The only news I have to report on is my personal exploration of the ideas.
There's a name for seeking satisfaxion through possessions: consumerism. Anti-consumerism really appeals to me. (I had the misfortune to be thirteen years old when the movie Fight Club came out.) Not only does it make you less mentally vulnerable, but you contribute less to global capitalism, with all its well-known side-effects of exploitation, pollution, and so on.
Simple living also saves a lot of money.
You only need so much. As Epictetus says in verse 39 of the Enchiridion, in the same way the foot determines what kind of shoe is needed, the body determines what kind of possessions are needed. A human needs about 1.5kg of water a day, 1.5kg of food, and about 30m2 of living space. What are you going to do with more than that? I think it's stupid to pile up a bunch of unnecessary stuff, so any time I hear some celebrity bought a 2000m2 mansion, I am always very impressed; these people must be absolutely enormous.
Possessions come with responsibility. They demand time, money and attention to clean, maintain, store, pack, unpack, operate and generally deal with. If you have a big, grand house, you better be prepared to spend a lot of time calling plumbers, roofers, electricians, exterminators etc. to deal with it. If you have a small apartment, you can use that time to learn to play the ukelele.
Consumerism is the habit of falling for advertizing campaigns that associate a company's product with an inner desire (for status, love etc.). There is no love in a can of Lynx; that's a Madison Avenue magician's illusion. The danger is a cycle of going from one empty promise to another. Satisfaxion does not come from possessions; it comes from the inside.
Now the downsides.
If you live in a consumerist society (e.g. modern Western society), you're likely to be involved in games that use possessions as a yardstick. Certain jobs require certain clothes and accessories to impress people. This is a key strategy of consumerism: you buy things not because of what the thing itself does for you, but because of the status other people grant you for having it. Status symbols. I think Karl Marx called it fetishization.
Another problem is that people will try to buy gifts for you, and their nose sometimes gets out of joint when you tell them you don't want anything. The best way to get around this is to say in advance that you want tickets, or other gifts of experiences rather than possessions. (You can tell people to donate to charity instead of giving you a gift, but in my experience, they don't generally believe you.)
Ending the experiment and going back into normal consumerist life will mean spending a few thousand on gadgets and a wardrobe.There are different types of rules you could set:
Clothes driers. Seriously, what the fuck are these things for? They dry your clothes? Your clothes just dry naturally anyway if you do nothing. Buying a machine to dry clothes is like buying a machine to make the sun rise. I don't need a big, expensive, power-hungry machine to do nothing. They wear your clothes out faster too.
Lawnmowers. I simply do not believe in lawnmowers. A scythe is simpler, cheaper. Better yet, use a herbivore. Why would you spend money on petrol and lawnmower maintenance when you achieve the same result with a goat that will pay you in milk and meat?
Excessive clothes. At time of writing, I own six T-shirts, three shirts, and two pairs of jeans. I find this to be a bit much. I get annoyed by the burden of laundry. Over the past few years, I have normally had two or three t-shirts and two shirts.
Curtain hooks. I once talked to a lady in Ireland who does nothing but sew curtain hooks to curtains. She charged hundreds of euros for this. In less complicated countries, curtain are secured by wooden hoops through a wooden bar: cheaper, more solid, more simple.
(These examples are just to make a point about consumerist society. You can think of others.)