After Willow Creek realized that what they were doing as a church was not helping people grow spiritually, they set out to find out what does help. Four years, 200 churches, and 80,000 surveys later, they found this:

Everywhere we turned the data revealed the same truth: spending time in the Bible is hands down the highest impact personal spiritual practice. More specifically, “I reflect on the meaning of Scripture in my life” is the spiritual practice that is most predictive of growth. . . . Reflecting on Scripture implies a contemplative process, one of thoughtful and careful deliberation. This practice of “reflecting on the meaning of Scripture in my life” is about using God’s Word as a mirror that reflects back the truth of Scripture on the actions, decisions, and defense of one’s daily life. This is not about skimming through a Bible passage or devotional in a mechanical way. This is a powerful experience of personal meditation that catalyzes spiritual growth, starting at the very beginning of the spiritual journey.

—Ham, Ken (2009). Already Gone (Kindle Locations 1671-1678). Master Books. Kindle Edition.