"Routine", as an uncountable noun, refers in general terms to an ordered way of life.  Think of it as an abstract idea that's the opposite of "chaos".  

"A Routine", as a countable noun, refers to one specific schedule of regular tasks which a person follows.

@ Emily 

You wrote: "The noun routine can be countable or uncountable. In more general, commonly used, contexts, the plural form will also be routine. However, in more specific contexts, the plural form can also be routines e.g. in reference to various types of routines or a collection of routines."

You really should show from where you lifted someone else's work.

https://www.wordhippo.com/what-is/the-plural-of/routine.html

Thanks Su.Ki.

Very clear explanation.

1. I love occasionally to aberrate from routine.

2. A project is something temporary done only once, it is not a routine.

In this examples Routine is countable(2) and uncountable(1). What is the difference in meaning of "Routine" in those examples?

Thanks Emely,

I am interesting when use "a routine" as countable vs "routine" as uncountable.

What is difference in meaning?