"How can a young man keep his way pure?  By guarding it according to your word."  --Psalm 119:9 

We guard our way and keep it pure by:  1) seeking the Lord with our whole hearts (Ps. 119:10), 2) not wandering from his commandments (Ps.119:10), 3) storing up his word in our hearts (Ps. 119:11), 4) declaring all the rules of his mouth (Ps. 119:13), 5) delighting in his testimony (Ps. 119:14),  6) meditating on his precepts (Ps. 119:15), 7) fixing our eyes on his ways (Ps. 119:15), 8) delighting in his statutes (Ps. 119:16), and, 9) not forgetting his word (Ps. 119:16). 

What God calls us to do, he gives us his enabling to do it.