Psalms and purity

How can a young person stay on the path of purity? 
By living according to your word. 
I seek you with all my heart; 
do not let me stray from your commands. 
I have hidden your word in my heart 
that I might not sin against you.
 
- PSALMS 119:9-10


John 3:16 - For God so loved the world that He gave His one and only Son, that whoever believes in Him shall not perish but have eternal life.