If you're tired of the same old breakfast of bran flakes and orange juice, vary your routine—put some banana slices on those bran flakes. You can vary the routine by changing the details but keeping the basics the same.
Use the verb vary when you're talking about changing up your usual routine. If your schedule changes at work, you might have to vary your sleep habits. A good dye job will vary the tints a little to look more natural. The ambiance at Olive Garden varies from restaurant to restaurant, but the unlimited breadsticks are always delicious. You'll probably recognize the root vari, which shows up in other words with similar meanings, like various, variable, and even variegated.