This couldn't be more true in business. There is a tendency to worry about every little aspect of your business. And, as the founder (and sometimes sole employee) you SHOULD worry about all aspects of your business. But, you also need to have faith. It isn't the deal falling through that will kill your business. It isn't the employee who doesn't live up to your expectations that will make you falter. It isn't even the legal snafu that will destroy you.
It is your inability to react to these things that will keep your business from succeeding. Sometimes, branches break. You have to be able to fly when it happens.
There is a second meaning to this saying. Never stop learning! It is your ability to fly that will save you from a thousand different problems that arise.
Keep learning and have faith in yourself, and you...like the bird...will land on your feet no matter how many branches fall from beneath your feet.