First of all..I would like to say that Gmail is out of Beta..yep..After a long time when they have integrated the best of world in their email system,
In order to access this feature,sign in to your account and select ' Change Password Recovery Options ' enter your cell phone number and click ' Save '
The Next time you forget your password, enter your username on the password-assistance page, and Google will text you a recovery code. No need to check another email account or even leave the page.
In general, it's a good idea to add as many password recovery options to your Google Account as possible, like a secondary email address and security question. And don't forget to keep them up-to-date.
Afterall,we all make mistakes :P