How often do you change your principles ?

In your life there comes a time when you need to adapt your principles or you need to fully change them [ and this depends on the situation ].
For instance one will steal to eat because there’s nobody around whom he can ask for food [ this was just an example do not debate only on this ].

Based on what do you change your life beliefs ?
Why do you need to change your principles ?
Do you change them just to suit you in given circumstances ?

Please discuss and try not to flame each other.
Thanks.