Twyla Tharp is a choreographer who lives in Manhattan. 
Every morning she gets out of bed, puts on her workout clothes and goes downstairs to hail a cab to go to the gym. 

Her “workout ritual” is hailing the cab. 

Once she’s in the cab, the cab takes her to the gym and she works out. 

Habits are cues -> actions -> outcomes. The cues can be completely unrelated to the outcome you’re trying to achieve. 
Twyla’s habit is actually a series:

Alarm -> Get Dressed -> Hail a cab

By the time she’s awake, the choice of whether or not she should go work out has already been made and acted on.

Not everyone can just hail a cab to take them to the gym, but the approach to the ritual can be the same. 

The more consistent the cue and the less effort required for the initial actions, the easier it is to establish a habit.

Here’s an outstanding 3 minute animated version of the concept from: epipheo. 

H/T:

I learned about Twyla Tharp’s workout habit from: James Clear.