Thomas Watson writes the following paragraph in his little book, Heaven Taken by Storm: Showing the Holy Violence a Christian Is to Put Forth in the Pursuit of Glory:
Even where sin has received its deadly wound and is in part abated, the work of mortification is not to be laid aside. The apostle persuades the believing Romans to mortify the deeds of the flesh (Rom. 8:13). In the best of saints there is something which needs mortifying– much pride, envy, and passion; therefore mortification is called crucifixion (Gal. 5:24), and is not done suddenly. Every day some limb of the body of death must drop off. Nothing harder than rock (saith Cyrill), yet in the clefts thereof some weed or other will fasten its roots. None stronger than a believer, yet do what he can, sin will fasten its roots in him, and spring out sometimes with inordinate desires. There is always something which needs mortifying. Hence, Paul did beat down his body by prayer, watching, and fasting (1 Cor. 9:27).p. 10
Like weeds wrapping their roots around rocks, the strongest of Christians will still find sin “fasten its roots in him.” Watson speaks rightly, therefore, that killing sin is a daily and constant duty, a lifelong crucifixion. We must fix our eyes fully upon our Savior, beating down our flesh through prayer, watchfulness, and fasting.
What sin is presently growing roots around you? Are you daily mortifying these “inordinate desires?” Are you watchful and vigilant against sin? Do you guard yourself through prayer and fasting?