You know that thing about how it takes 21 days to develop a new habit?  Forget it, says former NFL star, Broadway writer/performer, and motivational genius Bo Eason.

According to Eason, the magic number is actually 66 days.

Bo ought to know. He’s been developing serious habits all his life, which took him from an being an undersized, oft-rejected high school football player to a top safety in the 1984 NFL Draft. And a 9-year pro football career to boot.

Eason’s new book, There’s No Plan B for Your A-Game: Be the Best in the World at What You Do, has just been published by St. Martin’s Press and lays out his strategy for achieving personal greatness.

When a career-ending injury left Eason wondering what to do next, he decided to be the best in world at writing and performing, so he created his own one-man show, Runt of the Litter, which ran for more than 1,300 performances in New York.

Eason is a devotee of the concept that it takes a lot of years to be an overnight success—15 or 20, to be exact.

“When I decided to be an actor,” he recalls, “I asked myself, who’s the best actor in the world? Al Pacino. So I spent three hours with Pacino shooting pool in his home, and he explained to me that it took 15 or 20 years to master performing. I had no problem with that time frame, because that’s exactly what I had done with football.

“When I asked him why he gave me all that time, he said, ‘Everybody I meet asks me how to get famous or how to get a role. You’re the only one who ever asked me what it takes to be the best.’”

Eason applies his philosophy of taking a 20-year long-term plan by breaking it down into 66-day increments.

“I always thought it took longer than three weeks to lock in a new habit, and then I saw research from the University of London showing that 66 days was the optimal number. If you do something for 66 straight days, on day 67 it’s impossible to do the opposite. So if you’re wondering how to stay motivated over a 15 to 20 year timeframe, part of the key is to develop one new skill or set of skills every 66 days.”

Eason’s son Axel has a long-term dream of his own—to be the first athlete to play in both the NFL and the NBA. To that end, father and son have created 66-day training blocks so that Axel can develop the skills he’ll need to make his dream a reality.

“Right now, we’re focused on using the ground,” Eason says. “Athletes like Michael Jordan and Barry Sanders were the best at pushing off the ground, which gave them unique ability in terms of speed and jumping. So we’re focused heavily on that for these 66 days, and then we will move to the next topic once this gets locked in Axel’s system.”

Eason says that most people in the world appear to be committed to mediocrity because they don’t set goals for themselves, they don’t make declarations that inspire them to move forward, and they don’t have a plan. His goal is to be the best at whatever he does and to inspire others to live the same way.

“Thoroughbred racehorses only do one thing,” Eason notes. “They run fast. They love to run fast. It’s who they are. They’re the best at what they do and they love being the best. That’s why we call them thoroughbreds.

“It’s not enough to say, ‘I want to be one of the best.’ Or ‘I want to be really great at something.’ Don’t hedge on simply being your best. That’s the thing that motivates you to find what’s really inside of you.  Instead, you’ve got to commit to being the best.

“Before every game and before each of the 1,300 performances of my show,I would look at myself in the mirror and say, ‘For the next amount of time, I’m going to be the best safety or performer or whatever, that the world has ever seen.’ Did I ever get there? Maybe for a second here or a minute there. I’m just asking myself to give everything I’ve got, and maybe for one minute, I’ll be the best safety in the history of the NFL, or the best performer.

“Why would you want to cheat yourself out of an opportunity like that?”

To learn more about Bo’s book, There’s No Plan B For Your A-Game go to boeasonbook.com