How can a young person stay pure?
By obeying your word.
I have tried hard to find you—
don’t let me wander from your commands.
I have hidden your word in my heart,
that I might not sin against you.
I praise you, O  lord;
teach me your decrees.
I have recited aloud
all the regulations you have given us.
I have rejoiced in your laws
as much as in riches.
I will study your commandments
and reflect on your ways.
I will delight in your decrees
and not forget your word (Psalm 119:9-16).
How much time to spend in God’s Word?  I’m often amazed at how little time people spend reading their Bible.  I know, I know… I’m a pastor.  It’s my job to read the Bible.  Blah, blah, blah.  In a study that came out in 2012, findings indicated that only 19% of churchgoers read the Bible on a daily basis; a similar percentage reported rarely/never reading it.  Only 14% said they read it once a week, 22% say they read it once a month or a few times a month.  In another study from 2013, the numbers were worse. 26% said they never read the Bible (even though 88% had at least one in the house).
How do we expect to grow in our life of faith, if we never engage with the source of our faith?  Now, I know some people will say something along the lines of, “Jesus is the source of my faith, not some book.  I’m just going to love people and do good.”  That’s nice.  You know what Jesus did?  He read Scripture.  He was familiar with it.  When he faced temptation in his life, he fell back on it.   How do I know that?  Because I read about it… in some book.  Apart from the revelation of Scripture, we don’t know much about Jesus or his teaching, do we?  It would then seem disingenuous to say that we aren’t tied to Scripture in an important way when it comes to our faith.
So spend time in the Word.  Read it.  Study it.  Allow yourself to be shaped by it.