So you, too, must keep watch! For you don’t know what day your Lord is coming.
Matt. 24: 42 NLT
Watchfulness is a passionate desire for the presence of the bridegroom which awakens within us a spiritual sensitivity to the signs of his soon arrival. This spiritual sensitivity is a heart connection with the Holy Spirit who graces the believer with insights and discernment concerning the times and seasons immediately preceding Christ’s parousia. A watchful attitude is characterized by being spiritually alert, holy and ready for Christ’s return, as opposed to spiritual dullness typified by worldly attitudes and sinful passions. (HT: Mike Bickle)
We must not only have faith in [Christ], but must wait on Him; not only must hope, but must watch for Him; not only love Him, but must long for Him; not only obey Him, but must look out, look up earnestly for our reward, which is Himself. We must not only make Him the Object of our faith, hope, and charity, but we must make it our duty not to believe the world, not to hope in the world, not to love the world. We must resolve not to hang on the world’s opinion, or study its wishes. It is our mere wisdom to be thus detached from all things below. . . .
They, then, watch and wait for their Lord, who are tender and sensitive in their devotion towards Him; who feed on the thought of Him, hang on His words; live in His smile, and thrive and grow under His hand. They are eager for His approval, quick in catching His meaning, jealous of His honour. They see Him in all things, expect Him in all events, and amid all the cares, the interests, and the pursuits of this life, still would feel an awful joy, not a disappointment, did they hear that He was on the point of coming.
John Henry Newman,  “Waiting for Christâ€