If you have no debt and live by the belief (as you stated) that you shouldn't have anything you can't pay cash for.....you don't need to worry about your credit score. You have no reason to have a great credit score if you do not ever intend on buying something on credit....so I wouldn't worry about it if I were you
A credit score is a score of credit worthiness....BUT it's also quite the game. You have to have credit to show credit worthiness and creating some amount of debt seems to increase your credit score (percentage of your credit utilized, not just having a lot of credit cards sitting with a zero balance).
Again, it's a game and really unless you are going to use your credit...why worry about a credit score. Enjoy being debt free and continue to pay cash for items

Have an emergency fund set up to keep you from having to take out loans....if you've made it this long without having to get a loan, you can continue to do it....just have that emergency money in place.