A friendly and positively sensitive animal regarded as man’s friend is the dog. Its alertness and abilities to detect strange beings and strange atmospheres make it useful and effective as a watch guard. A well-trained dog pays attention to the smallest details and is always on guard so that the enemy does not attack it unprepared. Scripture tells us that two contrasting forces are seeking the attention of man - God's Spirit and human's flesh. The flesh represents cravings or lustful desires that seek to satisfy the human body. The devil takes advantage of these desires, superimposing them on the human mind and tempting us to sin.
The devil, our enemy is looking to catch us off guard creating an avenue for him to attack us as a predator feeds on its prey. That’s why Apostle Peter warns fellow believers to be sensitive and be on the watch. The devil knows his job will be difficult if we are up and doing, fervent in the Spirit. He seeks to take advantage of the weakness of the human flesh - our inability to resist the need to gratify our lustful desires becomes the opportunity he uses to wreak havoc in our lives. 
This is why we must seek to walk according to the law of the Spirit to keep the enemy at bay. Being on the alert and watchful requires that we are conscious of the sly and crafty ways of the devil to escape falling into temptation. While we watch, it is important that we prayerfully guard our hearts towards God and trust Him to help us withstand the wiles of the enemy.

Dear Heavenly Father, I bless You for keeping watch over me. Thank You for keeping me alive in Your Holy Spirit. I pray that my ability to perceive things in the Spirit is increased as I study Your Word daily. Help me block every opportunity that the enemy is using to attack my life. Teach me how to temper my desires, Lord. May I receive the grace not to gratify the lust of my flesh but live and walk according to the dictates of the Spirit.
In Jesus’s name I pray. Amen.