I have told you these things, so that in Me you may have [perfect] peace and confidence. In the world you have tribulation and trials and distress and frustration; but be of good cheer [take courage; be confident, certain, undaunted]! For I have overcome the world. [I have deprived it of power to harm you and have conquered it for you.]
It still amazes me when I have tribulations, trials, distress or frustration. It shouldn't! But it does. Jesus warned us that there would be these things in our lives. Not just in this verse, but in many verses. I think it's because I hope for a pain-free life. I want to follow Jesus and have it all! But I do...He's overcome the world. He's deprived it of power to harm me. And He's conquered it for me. And He lives in me.
Give me a minute...I have to wrap my mind around this one.