When our zeal for Christ is glowing hot, spiritual disciplines are never a duty. Why? Because increasing our zeal is the equivalent to increasing our appetite for food. When we focus on dying to ourselves, putting away our sin, thirsting for righteousness, our appetite for spiritual food increases. By pursuing holiness, we are inevitably drawn toward talking with God and meditating on His Word. We naturally want to feed more on the food that our appetites are suited for. I firmly believe that this is why the New Testament does not focus on rigorous spiritual duty. In fact Paul warns against actions without love (1 Corinthians 13). Christ talks about meaningless prayers with false motives (Matthew 6).
What the Scriptures emphasize is holiness, which in the Greek means sanctification of heart and life. God wants us to set ourselves apart within our hearts and minds and dedicate our entire will to Him. When we do this, our desire for spiritual communion with God happens naturally (Galatians 5:16). Our natural desires for the world become supernatural desires for God. This is why the author of Hebrews said,
Strive for [...] the holiness without which no one will see the Lord (Hebrews 12:14 ESV).
If we find ourselves struggling to desire prayer and His Word, it is less likely a matter of discipline and more likely a lack of pursuing holiness and consecration of our hearts for the LORD.