If you use Gmail, you will notice at some point when you log into your account, that they will ask you to provide "Recovery Options".... this is a phone number and alternate email address.
Please do NOT ignore this by clicking "skip". Instead, please take a moment to provide them with your cell phone, and perhaps another cell phone number (like your significant other or a good friend) and if you have it, an alternate email address (that you could log into).
The reason is for password recovery and other account lock out assistance. Google (parent of Gmail) has significantly "hardened" their security procedures to the extent that if you do not provide one or both methods of recovery, you will NOT be able to gain access to your own account if you forget the password or there are problems.
This is because of so many "hackers" and intrusions from people pretending to be other people that are trying to hijack your Gmail account. If a "bad person" does gain access to your account, then s/he will have access to your entire email, contacts list, and more.
SEE the below for the procedure to manually perform the task of adding your Recovery info. Of course, if Gmail automatically asks you when you log in, then please do it then.