There is only so much room on your shelf. If you want to add something new to your shelf, you have to remove something already on it.
There are dozens of projects you want to work on, but the truth is that you can only reasonably handle a few projects at a time and retain your ability to do them well. If you take on too many projects at one time, not only will the quality of the projects suffer, but so will the quality of your life.
Working too many hours, not getting enough sleep at night, or feeling overwhelmed and overworked all impact your attitude and ability to execute quality work.
There is only so much room on your shelf
If you keep adding more and more projects to your shelf, stacking them higher and higher and balancing them precariously atop one another, it may work for a little while — but only for a little while.
Once you go too far beyond the capacity of the shelf and its support anchors, the entire thing will collapse under the burden of its own weight.
And so will you.