The World's Most Successful People Don't Actually Start Work at 4 a.m. They Wake and Work Whenever the (Heck) They Decide By Jeff Haden Contributing editor, Inc.@jeff

Apple CEO Tim Cook starts his morning routine -- not just his morning, his morning routine -- at 3:45. General Motors CEO Mary Barra gets to the office by 6 a.m. Best-selling author Dan Brown (The Da Vinci Code, etc.) gets up at 4 a.m., has a smoothie and a cup of bulletproof coffee, and then grinds away.

Clearly, waking up early works for them.

But not for everyone.

As Adam Grant says, "The world's most successful people aren't worried about what time others wake up. They wake and work on the schedule that works for them."

What seems right for early birds may not be right for you, because what time you start your day has nothing to do with your level of success.

Success is all about what you accomplish -- and, just as important, how you choose to accomplish it.

Early Birds

Most people who choose to get up early do so because they can take advantage of a few hours of solitude. Fewer interruptions. Fewer emails. Fewer phone calls. Starting work earlier than everyone else lets you be proactive, not reactive, and lets you set the agenda for the day instead of having one set for you.

Others choose to get up early so they make sure they get their workout in -- and take advantage of the mood-boosting effect of exercise. (Research shows that as little as 20 minutes of moderate exercise boosts your mood for the next 12 hours.)

Or maybe they just get up early because The Wall Street Journal says that 4 a.m. may be the most productive time of the day.

Later Birds

If you decide to start your workday at, say, 9 a.m., you can still structure your day in the most productive way possible for you. Simply create a routine that allows you to hit the ground running the way you want to run.

Maybe that means locking yourself away for a couple of hours. Maybe that means working from home, and then heading to the office. Or maybe that means shifting your quiet hours to the evening. No one says you have to start work before everyone else -- you can just as easily finish work after everyone else.

Maybe that means training everyone around you to understand that the first two hours are your hours.

While that might sound impossible, don't forget that everything you do "trains" people to treat you a certain way. Let employees interrupt your meetings or phone calls whenever they like... and people will naturally do so. Drop what you're doing every time someone calls... and people will naturally always expect your immediate attention. Return emails immediately... and people will naturally expect you to immediately respond.

How you act -- and react -- "trains" people to treat you the way they wish... so start "retraining" them so you can work the way youwork best.

The Most Successful Birds

When you start working doesn't matter. When you stop working doesn't matter.

What matters is what you accomplish during the hours you work -- and that means making an intentional decision about what time you get up and what time you start work.

Don't get up at a certain time just because Tim Cook does. Don't start work at a certain time just because Sallie Krawcheck does.

Figure out what works best for you.

Success has nothing to do with what time you start. Or what time you finish. Success is all about what you accomplish.

Make a conscious decision about what time to get up. Not a reflexive choice or a copy-cat choice but a thoughtful, smart, and logical decision -- based on what will make you most successful.

Because that's all that matters.