On God's side, he does not save us and then tell us to do the best we can. Rather, he supplies specific instruments through which he can nurture us. To be sure, he is not limited to these means, but he has chosen to use them as his primary and normal means of effecting Christian growth. I have yet to meet a vital, growing Christian who did not use these means of grace in one way or another. There will always be highs and lows, ups and downs, advances and declines.
Christians have good days and bad days like everyone else.
Not to admit that is to misrepresent the facts. There are mountaintop experiences, but they do not come every day. The key to Christian growth is not feeling but faithfulness. God has expressed his faithfulness by providing means of grace. We express our faithfulness by taking advantage of them.