From the additional notes to Charles Spurgeon's The Treasury of David, Psalm 119, verse 9. [Of course, all of this applies to young women, as well!]
Cleanse his way. The expression does not absolutely convey the impression that the given young man is in a corrupt and discreditable way which requires cleansing, though this be true of all men originally: Isaiah 53:6. That which follows makes known that such could not be the case with this young man. The very inquiry shows that his heart is not in a corrupt state. Desire is present, direction is required. The inquiry is— How shall a young man make a clean way — a pure line of conduct— through this defiling world? It is a question, I doubt not, of great anxiety to every convert whose mind is awakened to a sense of sin— how he shall keep clear of the sin, avoid the loose company, and rid himself of the wicked pleasures and practices of this enslaving world. And as he moves on in the line of integrity— many temptations coming in his way, and much inward corruption rising up to control him— how often will the same anxious inquiry arise: Romans 7:24. It is only in a false estimate of one's own strength that any can think otherwise, and the spirit of such false estimate will be brought low. How felt you, my young friends, who have been brought to Christ, in the day of your resolving to be his? But for all such anxiety there seems to be an answer in the text.
By taking heed thereto according to thy word. It is not that young men in our day require information: they require the inclination. In the gracious young man there are both, and the word that began feeds the proper motives. The awful threatenings and the sweet encouragements both move him in the right direction. The answer furnished to this anxious inquiry is sufficiently plain and practical. He is directed to the word of God for all direction, and we might say, for all promised assistance. Still the matter presented in this light does not appear to me to bring out the full import of the passage. The inquiry to me would seem to extend over the whole verse [that is, all eight verses in this section]. There is required the cleansing that his way be according to the Divine Word. The enquiry is of the most enlarged comprehension, and will be made only by one who can say that he has been honestly putting himself in the way, as the young man in Psalms 119:10-11; and it can be answered only by the heart that takes in all the strength provided by the blessed God, as is expressed here in Psalms 119:12. The Psalmist makes the inquiry, he shows how earnestly he had sought to be in the right way, and immediately he finds all his strength in God. Thus he declares how he has been enabled to do rightly, and how he will do rightly in the future. John Stephen.
I assume this John Stephen was the Presbyterian minister (1800-1881) whose publications included Expositions on the Epistle to the Romans and The Utterances of the CXIX Psalm expounded in a series of lectures.