One of our fellow bloggers who also tends to talk quite a bit about Japan recently married a Japanese woman and came to Japan to live after completing university. He was concerned about debts from his education and getting them paid off as quickly as possible. I told him that my husband and I had managed to save nearly as much as his entire educational debt in the two years since I quit my former job so I was sure he could get those debts dealt with pretty quickly if he was careful with how he spent his money. (All the money we save, incidentally, has all gone into savings for when we're old and grey and can no longer work.)
You might assume that we make a lot of money. The truth is that we do not and our rent is pretty high (110,000 yen). The money we saved during those two years represented about 35% of our income. We don't make a small amount of money, mind you, but my CH isn't in a high-paying job and I only worked 5-10 hours a week from home during the two years in which we saved that amount of money. The way we save a fair bit is by not spending what we get. This isn't as hard as it may sound, but it does take awhile to reach a mindset where living well below your means doesn't feel like a burden or sacrifice. For us, it evolved naturally so we've never found ourselves pining for things. I consider us very fortunate in that regard.
I've come to understand that there are 3 cornerstones to reducing your spending:
1. Cook for yourself from real (whole) food ingredients (never pre-mixed, pre-bagged, or pre-made).
2. Don't buy new clothes or shoes unless you need them (never buy because they are attractive to you or you think you'll look good in them).
3. Never shop to entertain yourself or to mitigate unrest in your life.
If you follow these, your spending will be dramatically reduced. Most people waste their money on incidental items they rarely need or use, convenience, and the momentary "high" of obtaining something novel. If you scrutinize the pleasure your spending habits bring you, you'll likely see very few of the items bring long-term pleasure or fulfill recurring needs. Most of the pleasure you get is from looking at the items, considering buying them, making the purchase, and carrying the bag home. Once the item is in your possession, there is definitely a letdown for many purchases.
Most people can't get past the idea of "deserving" the reward of buying something they want so they justify wasteful spending as a way of making working worthwhile. They feel empowered by the freedom of obtaining what they want when they want it and choose the immediate small sense of freedom over the long term freedom that comes from financial stability and security. I won't say that, if you hate your job and have to placate yourself by buying junk, it's probably time to consider a different job which doesn't make you as miserable but may pay less because I know that's unrealistic for many people. However, it is worth considering.
I'm not judging anyone for their spending habits, mind you. We all make stupid decisions for short-term benefits because life is hard sometimes and some little tidbit can make us happy for awhile. However, if saving money is important to you, you have to change your entire mindset about shopping and the acquisition of possessions.