For one, God is watching! He is Omnipresent, and He is Omniscient; that is, He is everywhere, and He is all-knowing (Ps. 139:1-12; Isa. 40:26; 46:10; Rom. 11:23; etc.)! Adam and Eve tried to hide from God, and although God "played along with their game of hide and seek," He knew (Gen. 3:8-10). Jonah tried to run away from God, but while he was on his journey, God was preparing a "mode of transportation" to bring him back (Jon. 1:17). God was present in the fiery furnace with the three Hebrew children (Dan. 3:24-25).
In addition to always being seen by God, His Word says that both His angels, and the fallen angels, are watching us. The Apostles Paul and Peter wrote:
"Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ; and to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ: to the intent that now unto the principalities and powers in heavenly places might be known by the church the manifold wisdom of God, according to the eternal purpose which He purposed in Christ Jesus our Lord" (Eph. 3:8-11).
"Unto whom it was revealed, that not unto themselves, but unto us they did minister the things, which are now reported unto you by them that have preached the gospel unto you with the Holy Ghost sent down from heaven; which things the angels desire to look into" (1 Pet. 1:12).
And finally, those who have not accepted Christ as Lord and Savior, those who are lost and bound for eternal separation from God, are watching us to see if our "walk" matches our "talk." God calls on us to live a holy life that will bring Him glory ("conversation" means "behavior" or "way of life" - Phil. 1:27; 1 Tim.4:12; Jam. 3:13; 1 Pet. 1:15; etc.)! Especially 1 Peter 2:12, which says,
"Having your conversation honest among the Gentiles...
that they may by your good works, which they shall behold,
glorify God in the day of visitation."