backup – Best approach to backuping program config files?

I have a program which looks for a config.json file where it reads needed sensitive infos like DB creds, different APIs creds, etc. I don’t upload the config file to the git repository because I understand it’s a bad approach, although it’s a private repository. Now I’m starting to fear the case that I by accident delete this file, or due to a failure in my machine, I could permanently lose it. My question is – what is the best approach I could use to have a constant secured backup for this file, considering that it may contain very sensitive informations?

Also I would like to specify that this config file is frequently changed (and may increase in size…).