1.  Routine is an adjective that describes a day.

2. Routine is the a noun which means the order and way you regularly do things.

Val

Leigh answer is 100% correct and 100% complete.

"Routine" can be an uncountable noun too, in a more abstract sense. See here (inc. 3rd example sentence).

https://www.collinsdictionary.com/dictionary/english/routine

Thanks Leigh, Richard and Chris.

I see my misunderstanding first example, but what about this:

1. I love occasionally to aberrate from routine.