Many people feel that these instructions of Jesus guarantee that others will take advantage of us. That would be true if there was no God. But when we follow these commands of Jesus, the Lord is on our side. He said in Rom. 12:19, "Dearly beloved, avenge not yourselves, but [rather] give place unto wrath: for it is written, Vengeance [is] mine; I will repay, saith the Lord."
When we fight back, we are drawing on our own strength. But when we turn the other cheek, we are invoking God as our defense. Once we understand this, it becomes obvious that these instructions are for our own good.
James 1:20, says that the wrath of man does not accomplish the righteousness of God. Regardless of how appropriate our anger may seem, and regardless of how we think our wrath could make a person or situation change, we will never achieve God's best that way.
When we defend ourselves, we stop God from defending us. It has to be one way or the other. It cannot be both ways. When we turn the other cheek to our enemies, we are loosing the power of God on our behalf.