One thing that's nice about rejecting consumerism is that you can consider retiring early. Owning a bunch of things like boats, fancy electronics, nice cars, this just doesn't do much for me. I'd rather be at home working on a skill. Maybe learn to play the piano. I talk about learning foreign languages. For me this is more enjoyable, and if you want to teach yourself of course it doesn't cost much.
If I really did live that kind of lifestyle I wouldn't need much on an annual basis to survive, especially if my house was paid off. Just doing some rough calculations I figure (since I'm married and will pay for two in retirement) that I'd need about $24K per year. That's probably a bit more than I need, but it gives me a cushion.
How much savings would be required to draw $24K/year? A conservative method is to resolve to draw no more than 4% of your total savings every year as income. You assume your savings could grow at 7%, inflation will eat 3% of the value, and so if you draw 4% effectively your savings doesn't ever diminish. You can draw 4% indefinitely. So this means I'd need $24K/4%=$600,000 in savings to retire.
A lot of people look at that and say it's all well and good, but when your savings is tied up in a 401k plan it doesn't really matter because you can't withdraw money from that until you are at least 55 if you decide to stop working. Right? Wrong. You can in fact draw from your 401k at whatever age you want as long as you are no longer working, and you still avoid the 10% penalty. The trick is you just must take the money as a series of equal periodic disbursements, like $24K/yr, and you would have to sustain that rate for a period of at least 5 years.
For me a $24K/yr lifestyle probably won't happen until my kids are through college. I want to help them with that because I don't want them to be debt slaves. That means I'll need to work for another 12 years (I'll be 50 then). At that point I should have more than $600K saved and at that point can afford to retire if I choose to. That feels good, and it's made possible by living differently than the typical American consumer.