You will care more about the things that aren't working yet, you'll push through the dip, you'll expend effort and expose yourself to fear.
When you have a lot of balls in the air, it's easy to just ignore the ones that make you uncomfortable or that might fall.
Success comes from doing the hard part. When the hard part is all you've got, you're more likely to do it.
And this is precisely why it's difficult to focus. Because focusing means acknowledging that you just signed up for the hard part.