Merriam-Webster's Dictionary defines repent as follows: "to feel or show that you are sorry for something bad or wrong that you did and that you want to do what is right; to turn from sin and dedicate oneself to the amendment of one's life; to feel regret or contrition".
Repentance is an inner change. It is an inner conversion that expresses itself outwardly. Genuine sorrow for offending God is often expressed in prayer, fasting, and good works. These are the 'fruits of repentance' that John the Baptist spoke about (Luke 3:7-14) - the result and proof of true conversion.