...to familiar environmental cues. 

They form when you engage in a behavior repeatedly in the presence of consistent stimuli.

• An environmental cue (that triggers your brain to initiate a habit);
  
• A behavioral response (the manifestation of the habit);
  
• A reward (that reinforces the habit).
  

...means changing the cue that triggers it.

Instead of focusing on developing the habit of “working out,” develop the habit of putting yourself in the position to work out regularly: get home, get into workout clothes, prepare you water, go to the gym. 

...of days to form a new habit.

Instead, habits come about gradually over time and in a non-linear fashion.

1. Knowing the basics about how habits form and how they work
2. Adjusting your perception about the habit you want to build - If the habit seems impossible, then it will feel harder
3. Planning for when things go wrong

While consistency is key, missing one or a handful of opportunities to practice the desired habit will not ruin your chances at establishing that habit in the long run.