Adam Clarke on Psalms 119:15

I will meditate -

12. He should encourage self-examination and reflection; and meditate frequently on God's words, works, and ways - and especially on his gracious dealings towards him.

13. He should keep his eye upon God's steps; setting the example of his Savior before his eyes, going where he would go, and nowhere else; doing what he would do, and nothing else; keeping the company that he would keep, and none else; and doing every thing in reference to the final judgment.