To gather with God’s people in united adoration of the Father is as necessary to the Christian life as prayer.

A commitment held only in private tends to thin out. What is claimed is that gathering with others who hold the same thing is not a supplement to the inner life but a requirement of it, because belief maintained alone drifts, and being in a room with people practising the same thing does something solitary conviction cannot. Whether or not you share the faith in question, the mechanism is familiar from anything people sustain together.

Look at what you care about most and whether you do any of it in company. If the answer is none, that may be why it keeps fading. Regular presence with others does more for durability than resolve does.