It appears impossible at times. A seemingly impossible task in a world splattered with sin and pain. Yet the desire to pursue purity is a noble struggle indeed.
As much as desire to, I cannot tell you that this struggle will get easier. Or if it will even get better. More socially acceptable. However, I can tell you that it is worth it. For, in the end, it is the issues that you have poured the most sweat, tears and blood into that will be the most valuable to you.
Concerning physical purity, there are things you can do to alleviate some difficulties.
The first is to avoid occasions that you know are tripping points for you. Keep in mind that these are incredibly personal. Stumbling blocks are as unique as you are. What may cause you to slip and fall could be an unnoticeable pebble in the road for others. If a recovering drug addict knows that a certain house would be conducive to regression, he should by all means avoid that house. So to, the child of God struggling to remain pure should avoid occasions of sin specific to the vice. That could mean not going over to a boy's house when you know that you two will be the only ones there. That could mean closing down electronic devices when you are the only one there to keep tabs on yourself. It could mean avoiding certain movies and music. Yet these situations can only be identified you.
Don't be afraid to use a two letter word that it seems we avoid more and more these days: "No." True, it may be awkward when you have to tell your friends that you aren't going to go see that movie. It may create some moments of silence when you tell the person you like that you can't come over, as much as every fiber of your very being is begging you to say yes. Brian Kissinger said, "It’s better to be awkward and avoid sin than to fall into sin because we’re afraid of looking or seeming weird."
Take advantage of Lent. It is through Lent that we deny ourselves small things as a practice field of denying ourselves the sinful desires offered to us by this world. So while not drinking coffee during the week may give you a HUGE caffeine headache (I know by experience that it does!), think of it as training to say no to something bigger when it comes.
Build up strong walls. Not physically. That would be weird. No - with people. Surround yourself with those who are in the same mindset as you are. A goal is more attainable when you know people are going to ask you about it. If you want to run a 5K, but you don't ask anyone for tips or tell them about your goal, how easy will it be to give up on that goal? The only person you are disappointing is yourself. But if you tell lots of people about it and train with them, the less likely you are to give up on your goal. Even if it's just asking someone to text you once a week and ask you how God is working in your life, you're much better off than trying to ride the struggle bus solo. Not to be a Debbie Downer, but the road to Hell is paved with good intentions.
The struggle is real....but so is the success. You can do this. I believe in you... and more importantly, so does God.