Despite the strategy you choose the important part to remember is the the key is consistency with that routine.

The difference between being in the zone and deep work is being in the zone happens by chance and after hours of procrastination but deep work is intentional and desired.

One ritual you could have is to define your workspace. Placing a "do not disturb" sign on your door or going to a coffee shop or library

Another way is to define specific boundaries. For example, you could completely disconnect from the internet or turn your phone on silent. 

You just need it to be a sustainable routine

We should track our habits to separate productive from unproductive time so we can spot patterns.

Adding routines and rituals to our day allows us to need our limited willpower less in order to maintain a state on unbroken concentration

The idea here is to use any downtime, such as when you are walking the dog or riding the subway or driving to work to do some deep thinking. You might try to use the time to solve a complex problem--Try to see sub-problems and break it down so you can solve it.

You can ask yourself action questions like "What do I need to do to get to my goals?"

The key is to be mindful with how you spend your time and give your brain a mental workout. This is stimulating your brain and allows you to focus on something demanding. 

Cal Newport says that our brains need space to wind down every night. Newport quits work every day at 5:30pm, no work, no email, no to-do lists. 

It's important to set limits. When you know you have to quit work at a specific time, it allows you to focus more intensely during your working hours.