When people get lazy in supplementing their faith they are like an almost blind person without his glasses. They can’t function with the realities of their world because they can’t see anything important as it really is. Remember, you will not automatically give due consideration to the Lordship of Jesus Christ, the reality of eternal destinies, the wonderful delight of present grace and mercy, or even the emptiness of present desires and temptations - you won’t interact meaningfully with these realities coasting on some conversion experience in your distant past. You’ll grow weary without the constant, Spirit-enabled exercising of diligence in your walk of faith.