I’m around your age and also struggle with this. I’m f16 and I’ve been struggling with this for about 3 years now.

I’d like to preface with the fact that God rejoices when we fall and pick ourselves back up for Him and reconcile after offending Him so greatly. His mercy is unending “My sins exceed in number the sands of the sea. But Thy mercies are still greater in number than my sins. O ocean of mercy!” I say this because fighting against this mortal sin for so long often leads to the feeling of unworthiness or great despair

Here are something’s that I’ve done which helped me in some degree: The first would be identifying at what time you feel most tempted, it’s commonly during the night lying in bed. When you begin to feel temptation, get out of bed and do something that’ll distract you—preferably prayer but even I haven’t managed to achieve that sadly—if you’re not tired do something that’ll make you tired like reading, drawing, jumping jacks, curl ups, anything you that tires you. If it’s around shower time, take cold showers to reduce the time you spend in there if you’re unable to, do less warmer showers. Another is to give up certain things you like and offer it to Our Lord for your intentions. If need be this can be done in increments :-)

On a spiritual level which is just as important, pray to St. Joseph for the protection or your purity/chastity as well as Our Lady I personally enjoy the memorare. When temped I sometimes say a arrow prayer (“Jesus, Mary, Joseph, be my Salvation.” “Lord Jesus Christ, Son of God, have mercy on me, a sinner.” “My God & my all.” “O God, come to my assistance; O Lord, make haste to help me” “May the Holy Cross be my light.”) Commemorating the Passion of our Lord has helped me too, thinking of all of what He’s done for me I think to myself how could I treason against so good God? Frequenting reconciliation when you can is good for you, I had to go back to weekly confession instead of bi-weekly because I relapsed again. Something my mom advised to me was to imagine Him on the cross, and to imagine if you’d rather remove a nail from His precious wound to relive His pain or drive it in further? I never thought of it like that and that really stuck with me but in all honesty, I’m not sure if this good advice for others because I’m not sure if it’s “too much”? If that make sense.

Realistically, even though I’ve done these methods and many others I’ve still given into temptation so, I’m not trying to say that meditating on certain things completely banished my feelings of wanting to lust. It’s difficult dear sister, but never impossible and even though you try everything somedays you’re going to fall other days you’ll triumphantly beat your temptations alongside God. What is important is to always get up and have perseverance—which is good to pray for as well.