God of Promise - Horton on Sanctification

"As Paul warns, we do not receive justification and forgiveness by grace alone, through faith alone, because of Christ alone, and then go on to sanctification as a matter of personal achievement (Gal. 3:1-4). In the new covenant, all of the blessings have Christ and his obedience as the only ground qualifying us as heirs. Not some of the blessing, but all of the, are comprehended 'in Christ.' This spells the end of both legalism and antinomianism: none of the blessings are the result of our own achievement, and at the same time, those who inherit the blessing of justification are equally beneficiaries of regeneration and sanctification." Michael Horton, God of Promise. P. 76.

Are not justification and sanctification both driven by law/gospel?

"There are many things in the Christian life that are useful and assist us in our walk. Disciplines of prayer and Bible reading, fellowship with believers, evangelism, and social concern are habits that the individual and the church cannot live without. Yet the Word and the sacraments are distinguished from all else as means of grace. While prayer is, as the Heidelberg Catechism puts it, 'the chief part of gratitude,' it is something that moves from us to God, while in preached Word and sacraments, the movement is from God to us." Michael Horton, God of Promise. P. 162.

Why is it that we often more attached to the self-help books on the Christian book table than the means of grace that God has provided for our sanctification (e.g. the preached Word, the Lord's Supper, Baptism, prayer)?