Google login issues

I have a gmail account that I rarely use. I just tried to log in and it required me to give it a phone number to ensure that it's me, even though I gave the correct password and username on the first try. I did not ever give this gmail account my phone number until now- I could not log in without having them send my phone a text, and I had to give them my phone number. Obviously if someone was maliciously trying to access my account this would be a useless defense measure, and I don't want to give google my phone information every time I use this account. How can I prevent this from happening when I log in again?