do you do any rituals to make it psychologically easier to deploy your code into production / replace an existing working system?

Open a beer and go into zero fucks given mode

That's where tests are for - peace of mind. Write those. Integration above unit

Tell myself it's easy and fast to roll back, just do it.

@donkulator kinda yes - but you should also check with coverage if every line is hit after running tests. I recently had a coverage of 99.7% and that last not hit 0.3% was a bug indeed. Coverage is amazing stuff. So underrated. It's the only way to know if your tests have the right reach

Yes, TDD and CICD