Repentance is a gift of God, not something that we can work up by ourselves through our own efforts. Of course, the same can be said of anything good that we might accomplish (notice Ephesians 2:8-10 once again; also consider Acts 5:31, 11:18, and 2 Timothy 2:25).
Repentance is demonstrated by actions. The word itself has the sense of “to change one’s mind” or to “turn around and go another way.” Repentance is not just feeling sorry for what you’ve done, though that may be a part of it. But sorrow alone will not accomplish anything. As Paul points out:
Godly sorrow brings repentance that leads to salvation and leaves no regret, but worldly sorrow brings death. (2 Corinthians 7:10)
In contrast, you have the example of Judas in Matthew 27:3-5 who kills himself in his sorrow, but that is something other than repentance. Likewise, Esau was sorry he’d lost his birthright, but it was something other than true repentance, too (see Hebrews 12:16-17). Repentance produces certain actions; that is, a person who is genuinely repentant will change his behavior. He or she will not continue doing the same sin any longer. For instance, if a husband is guilty of beating his wife, the wife should leave, not just forgive him and continue getting beaten up. If the husband had genuinely repented, he would not continue to beat up his spouse.
Likewise, the difference between genuine repentance and someone just going through the motions is pretty obvious. The one going through the motions will reluctantly do what is requested, but only because he or she wants to avoid being hassled. A genuinely repentant person is appalled by his or her actions and desperately wants to do anything that he or she can to “make everything right again.” If you asked a genuinely repentant person to swim the ocean, they wouldn’t hesitate or even question the request. A genuinely repentant individual seems to be fleeing whatever sin they are guilty of, as if terrified by it:
See what this godly sorrow has produced in you: what earnestness, what eagerness to clear yourselves, what indignation, what alarm, what longing, what concern, what readiness to see justice done. At every point you have proved yourselves to be innocent in this matter. (2 Corinthians 7:11)
Produce fruit in keeping with repentance. And do not begin to say to yourselves, ‘We have Abraham as our father.’ For I tell you that out of these stones God can raise up children for
Abraham. (Luke 3:8)
Also, a genuinely repentant person tends not to try to hide his or her guilt.