This came in a while back:

Help. I am trying to understand the nature of repentance and I think I am tying myself up in knots. I appreciate that faith is trusting in the promises of God. But the call to repentance fills me with difficulty. On one hand it seems something I am incapable of performing (due to my inability) and if there is a measure of repentance I will never reach it. But I suspect I misunderstand the term. If it is related to being sorry for sin then I will never be sorry enough, if it is related to turning I will never be able to turn enough. Am I simply to believe that my sins are forgiven based on the promises of the gospel or is this 'gospel law' (repentance) necessary to true faith?

I responded:

The short answer is : "change of mind"... this is the basic meaning of the turn (metanoia), and the consequences of that 'change of viewpoint' might be variously experienced as sorrow (over sins), delight and commitment (toward God), revulsion (over sins), relief (over forgiveness)... but the basic meaning is almost synonymous with 'changed belief'... in itself it doesn't refer to God, or sin, or whatever... and so you have to ask the question as to what are the implications/consequences of the change of mind... e.g. Acts 26.20: that they should repent and turn to God, performing deeds appropriate to repentance... notice that' repent' is DIFFERENT from 'turn to God', and that it is DIFFERENT from 'doing deeds'... and in Acts 20.21 it is 'repentance toward God (change your minds about what God is like) and faith toward the Lord Jesus Christ (confidence in His person and work specifically, as the agent of God)... like I say, sometimes (only sometimes) the idea of 'regret' is associated with it, but only because that regret is a 'fruit of repentance' (matt 3.8)...so, you might go back through the passages on repent and read them this way, and see if it makes more sense..