How to reduce stress in pets?

I don't know how it goes with other pets but I have read somewhere that dogs are accustomed to living within a certain pattern, a structured or an organized schedule, if I must say. Everything for them is routine. They eat, play, and sleep at a specific time and they do almost the same things everyday. Now, if anything different happens outside of that routine, that's when they get stressed. They get quite confused not knowing what to follow and what to do. So, I guess, let's reduce changes when it comes to our dogs so that they won't get stressed.