Admin.password reset

Okay I know this has been posted here numerous times before but if you could help me out please. I am running the current version of mountain lion. I would like to omit my log in password. So when I go into system preferences it asks for my password. and I DO type it in correctly, but it will not accept it from there. So now what? this something entirely new to me. Many thanks.

Never mind I figured it out.
I would just like to know how I lost it in the first place!

Boot into ML recovery by holding down Cmd and R. When it boots up, hit the utilities menu and open terminal. Type resetpassword and hit enter. You'll be able to reset the password from there, just in case you forget it again