God did not design our hearts with the ability to bear the burdens that our flesh demands. The more a person places these burdens on their hearts by becoming consumed by trying to be fulfilled through fleshly behavior are actually falling into a trap. All unbelievers are in this trap already. Christians are delivered from this trap at salvation, but can fall into again by not crucifying their flesh and becoming consumed by their flesh.
11 And do this, knowing the time, that it is already the hour for you to awaken from sleep; for now salvation is nearer to us than when we believed. 12 The night is almost gone, and the day is at hand. Therefore let us lay aside the deeds of darkness and put on the armor of light. 13 Let us walk properly as in the day, not in carousing and drunkenness, not in sexual promiscuity and sensuality, not in strife and jealousy. 14 But put on the Lord Jesus Christ, and make no provision for the flesh in regard to its lusts. Romans 13:11-14 (LSB)
Genuine Christians are marked in this life by a spiritual journey that God uses to sanctify them. Sanctification is the process whereby God removes Christians from the pollution of the world and conforms them unto His holiness. I have had some emergents and neo-evangelicals attempt to deny this as true for all Christians. They claim that only God is Holy and there is no call by God for His people to repent and mortify their sins. Regardless of what these people say, the Word of God does contradict what they say.
While the Apostle Paul wrote the passage at the top of post, our Lord Jesus Christ spoke the passage below.