Behavior change takes time.
There are two meanings to this simple sentence, both of them are true.
Meaning 1: Behavior does not change over night. It may take time, days, weeks and months for a behavior to truly change. If you are looking to change a behavior of your own or of your small beings, prepare yourself with a healthy does of patience. What I know is the longer a behavior has been around, the longer it will take to change. Which also could be said, the newer a behavior is that you wish to change, the quicker it will be to change. Keep this in mind when your small beings starts engaging in a behavior that may be cute the first 50 times but you know will become frustrating for the next 4,000 times...like sticking their tongue out when the neighbor you don't like says hello.
Meaning 2: When committing to change behavior, you need to commit time to this change. It will require conscious and deliberate actions at times when you previously were working on autopilot. Make sure you are willing to be dedicated to this change. A few minutes a day can be enough for some behaviors (like encouraging your two year old to use the word no, rather than throw items she does not want) and sometimes more time each day is needed (like potty training). When you start to address a behavior change, it is best to see it all the way through; so make sure you have the time to dedicate.