Matt 26:41 Jesus said "Watch and pray, lest you enter into temptation. The spirit indeed is willing, but the flesh is weak."
We need to Watch & Pray. Let us see what this means. In general it refers to spiritual sleep.

GENERAL MEANING - SLUMBER - Spiritual Sleep
We must be watchfull and not slumber. Many people stay awake all night for a party or for a movie. But the moment they or someone prays or reads the bible they cant stop yawning and began to slumber. The bible in many instances refers to death when using the term sleep. In the book of acts someone dies after they fall asleep and fall. To fall asleep in Christ refers to becomming luke warm or away for God.
Act 20:9 As Paul was preaching, Eutychus was overcome by sleep; fell down from the third story and was taken up dead.
1 Cor 15:18 those who have fallen asleep in Christ have perished
1 Thes 4:13 I do not want you to be ignorant, brethren, concerning those who have fallen asleep, lest you sorrow as others who have no hope.

The example of THE GOOD, THE BAD & THE UNKNOWN
To better understand this we need to see the example of a real security/doorsman or watchman. When we are not watchfull we do not do our duty and attend to the RIGHT people, we fail to notice the WRONG people and we fail to identify the MISLEADING people. Below are things that we need to be watchful about:-

The GOOD - Jesus
We need to be watchfull and prepared for the second comming of Jesus. In the parable of the Foolish-Wise Virgins in Matt 25, it says in v5 the 10 virgins slumbered & slept. The same way, we too slumber. Eventhough they all slumbered only the 5 that were prepared met Jesus while the unprepared ones failed. So we must be prepared and watchfull for the second comming of the Lord.
Matt 25:13 Watch therefore, for you know neither the day nor the hour in which the Son of Man is coming
1 Pet 4:7 the end of all things is at hand; therefore be serious and watchful in your prayers.

The BAD - Enemy/Satan
We must be watchfull and vigilant against the enemy. In Matt 13:25 it says when we sleep the enemy comes and plants weeds in our fields. The enemy is just waiting for a moment to devour us.
Col 4:2 Continue earnestly in prayer, being vigilant in it
Matt 13:25 while men slept, his enemy came and sowed tares among the wheat and went his way
1 Pet 5:8 Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour.
Num 23:24 people rise a lion; not lie down until it devours the prey, And drinks the blood

The UNKNOWN - False Prophet
We must be watchfull and alert to discern people. In todays world its not people of other faith, its not the cults, its not the wrong denominations, but the false prophets who come from the right doctrine, they look good, but they are false.
Matt 7:15 Beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ravenous wolves