Proverbs 25:28 If you live without restraint and are unable to control your temper, you’re as helpless as a city with broken-down defenses, open to attack.

Every car has break, infact there are two types of breaks, the leg break and the handbreak. The purpose of break is to be able to stop the car when there is need to restraint the car at any time. Without this, a lot of accident and death would have happened, just imagine car without a break.

Without self control, we are like a car without break. Self-control is like a fence around a house. It is also part of the fruit of the spirit, it's in your spirit, you just need to acknowledge and exercise it. A man without self control will have many trouble, this I have seen. 

Proverbs 25:28 Whoever has no rule over his own spirit Is like a city broken down, without walls.

It is not only on bad things that we are to exercise self-control, most people are likely to think in terms of sexual appetite, etc, but even when it comes to good things. You can exercise control on what you say, where you go, who you relate with. You can do this over your spendings etc.

Your major battle in life is mostly not against bad things, but bad things appearing as good. There is always something looking good outwardly that are traps in disguise. If you made such mistakes like me, forgive yourself, move on and exercise self-control on matters of life. No matter how much clarity of the vision you have; exercise self-control, give things time and observe well, light will shine.