Flow. It's that ultra sweet spot in our day when we hit a rhythm and our work hums optimally and we find "the zone" of  productivity.

That's a familiar feeling. Right?

Not so much, according to Cal Newport, author of Deep Work: Rules for Focused Success in a Distracted World. He writes that ability to perform deep work, to get into our flow, is becoming increasingly rare at exactly the same time it is becoming increasingly valuable in our economy.

The problem is three-fold. First, finding our flow may not come naturally or easily. Second, training ourselves for deep work doesn't happen with a snap of the fingers. And third, our always-on, distraction-filled days and nights stack the odds against deep work despite our best intentions.

Yet, and this is a big yet, those who cultivate the skill, and make it the core of their working life, will thrive.

Which brings us to the good news. There's no restrictive, unilateral regimen to get better at deep work. The practice of learning it can accommodate a variety of schedules and personality types, from early risers to multi-taskers, and from limited to open availability.

The bottom line? Three to four hours a day, five days a week. That's the threshold of deep work that we're aiming for. When those 15 to 20 hours are uninterrupted and carefully directed, and when they have our full powers of concentration, you'll be surprised at both the quantity and the quality of valuable output you can produce.

Here's how it's worked for me and my business, at various stages of my professional and personal life. These three different routines and rituals, each designed with the science of limited willpower in mind, fit my evolving circumstances so that I'm continually able to find my flow.

Bimodal: When it's all or nothing.

This philosophy asks that you divide your time, Newport writes, dedicating some clearly defined stretches to deep pursuits and leaving the rest open to everything else. Dedicate a four-day weekend to deep work, say, or take a summer sabbatical. Channel your inner monastic for a limited stretch of time. Afterwards, return to regular accessibility.

Rhythmic: When you need to achieve deep work in a standard office job.

Set a time and a place for deep work, and make it a habit. The idea is to remove the obstacles of "when" and "where," so the cue for deep work is triggered in your brain. My regular routine (when I'm not on the road in irregular time zones) is to rise early and maximize the 5 to 7 am window, when I'm at my personal peak of energy and clarity for the day. It's when I "eat the frog," as the saying goes, and get the most challenging task of the day done first.

Journalist: Deep work on demand.

My career path in wine started, twelve years ago, with 20 minutes a day. As a new parent to twin boys, while also working as a journalist, I recognized that my day was punctuated by a few 20-minute windows of time -- while the babies were taking a nap, for example, or in between meetings at work. Rather than sit down for a cup of tea or scan the headlines, I figured out how to use those 20 minutes to advance my goal of writing full time about wine.

What I could do in 20 minutes, it turned out, was make serious headway toward a blog post about the wine I was drinking that day. Those blog posts, strung together, lived in a website called 365 Days of Wine, and that platform became my calling card for more and more paid assignments.

The Journalist philosophy of deep work follows the same principle, namely, fit it into your schedule whenever you can. The ability to "switch on" your deep work muscles is, surprisingly, less challenging than resolving to actually use the free time in your day on purposeful work.

A tip: "free time" is what you'll find when you redirect attention away from social media scans.