You have heard that it was said, 'You shall not commit adultery.' But I say to you, everyone who looks at a woman with lust has already committed adultery with her in his heart. (Matthew 5:27-28)
I know my limits. Take chocolate. I can't eat just a small bag of chocolate chips. I go for a bowl. And sometimes a second. That's why I ask my wife not to buy more than a small bag at a time.
Chocolate is bad enough, but lust – that's an entirely different story. That's a potential killer. I'm embarrassed to admit it took so long, but I eventually learned my limits there, too. And while I might fudge now and then with chocolate, I am meticulous to avoid situations where my eyes can open my mind to unholy images.
That's why I don't go to the beach or pools. I refuse to place myself where half-clothed women routinely stroll. I avoid cable television. Most of what networks broadcast is bad enough – but it's impossible to avoid R-rated commercials. I keep my gaze under tight control when I pass magazine racks and keep my eyes from wandering when a fashionable woman crosses my path.
The Holy Spirit will live only in a pure heart. That's one of the reasons St. Paul told the Corinthians " . . . let us purify ourselves from everything that contaminates body and spirit, perfecting holiness out of reverence for God." (2 Corinthians 7:1)
As for me, I've discovered part of perfecting holiness is knowing – and living within – my limits. Which is why I often pray something like this:
Lord, how can I keep myself pure unless You reveal my weaknesses – and then strengthen my heart to obey You? Oh, Holy Spirit, make this the desire of my heart.