Your personal finances is more personal than financial. It is about properly allocating your financial resources (e.g. money) to be spend wisely- not emotionally.
Restraint is defined as the act or process of holding back or hindering from action.
Restraint is about thinking first before spending. Restraint is your own “personal finance due process” system. Restraint makes you ask yourself- “Do I need this?”. It is not about being a cheap skate or miser. Instead, it is about carefully using your own money they way you want it.
Now, when you acquire the habit of restraint in your personal finances, you will start to use in cash in all your transactions. There is a strong emotional attachment towards cash than credit cards. You are less likely to freely buy something with cash since you have a limited supply in your purse or wallet. That is where the principle or habit of restraint works in your favor. When you use a credit card, you just have them slide your card and you sign something. It is much too convenient. More importantly, there is little of no restraint when using your credit card. You may use your debit card but personally I prefer to use cash on all transactions (e.g. groceries, gas, etc.).
Naturally, you will pay by writing a check or electronically transfer payments on your bills (e.g. electric, gas, water, etc.). On your day-to-day activities, you should use cash.
This is a good time to start to incorporate the principle of restraint in your favor. Later, you will be able to reap the benefits of restraint by acquiring the disciple of delayed gratification- which is a higher level of restraint.