From Will:

From the book “Alone with God” by Michael Warden.

It is possible to lose the Promised Land once it is gained, but in only one way - through idolatry. Idolatry is worshipping anything other than God. Such idols take many seductive forms - family, career, entertainment, comfort, money, pleasure, education, and even religion. Pride itself is a very common form of idolatry - the worship of self.

The Promised Land is gained through battle, and it is kept through diligence and humility. That is why the Scripture rightly says, “Watch over your heart with all diligence, for from it flow the springs of life” (Prov 4;23) The springs of abundant life are not in the external world. They are within you. And they can be stolen if they are not guarded. But how do you guard your heart? By staying humble in everything. Humble toward God, and humble toward others. In every circumstance, humility is your truest defense against the idols that want to steal our heart away.

Idolatry is an issue of the heart long before it becomes a matter of behavior. You can look perfectly holy on the outside and still embrace an abominable idol in your soul. Therefore, be diligent to guard your heart. Pursue humility in all things. This is your best defense. Fight for what is yours in the Lord. And stand guard over what you have gained.

One point of application:
Stay humble.