How to say: correct behaviour; become good again.

[Wai_Wai]

Say one did something wrong in the past. Now he realizes it is wrong and learns from the mistake. ""He will correct his behaviour"" and ""become good again."" <-- What is the common expression in written AND spoken English?
[as many common options as possible]


My idea is:
Written (formal):
I will mend my way
start life again with a clean slate/sheet

Spoken:
{no idea}

[westwind]

Originally Posted by Wai_Wai

Say one did something wrong in the past. Now he realizes it is wrong and learns from the mistake. ""He will correct his behaviour"" and ""become good again."" <-- What is the common expression in written AND spoken English?
[as many common options as possible]


My idea is:
Written (formal):
I will mend my way
start life again with a clean slate/sheet

Spoken:
{no idea}

Some more suggestions:

"Clean up one's act" i.e. I used to skip classes and party up all night, but I have since cleaned up my act after my parents' ultimatum of staying in school or ending up in juvenile detention.

"Turn over a new leaf" i.e. It looks like Bob has turned a new leaf from his drug-addiction days.

These two idioms do have the same meaning of improving one's bad/unacceptable behavior(s) from the past and starting to behave more responsibly/sensibly and to become a better person......

[JennyAnne]

Your idea for written formal was good, but you need these small corrections: I will mend my ways and start life with a clean slate. (Slate is better in my opinion, because saying you're starting over with a clean sheet brings to mind dirty sheets. I deleted the word 'again' because 'starting over' means again.)

Here's some other options:

I've repented of my past mistakes and have been reborn.

That carries a spiritual tone.

I've reformed and will rebuild my life for good.

I've reconciled myself with right and will balance my life accordingly.

For speaking there are tons of slangs and idioms such as:

Shape up
Get right
Go to plan 'B'
Shake it off and move up
Straighten up and fly right
Phony up
Dial back
Walk the straight and narrow
Fine tune
Debug
Upgrade