Impermanence. Everything comes all at once, is it going to stay forever? It's not. If one thing comes by itself or everything comes all at once, it's not going to stay forever. This is a key part of developing equanimity, to realize it's all impermanent, it's all just coming and going, coming and going.
Now, when I talk about the Unpleasant Physical Sensations technique, I mentioned that if there's two or three equally strong points, just choose one and work with it. This also works when everything happens at once. We can't fix everything at once, it's just not possible, even the Buddha couldn't do that one. So we actually have to choose one to try to fix. Now the brain can work pretty fast, and we kind of slide everything into a hierarchy, but when they all seem to be of equal value, just choose one and try to do it, and then try to get on to the next one, and then to the next one.
Worrying about it can be more the problem than actually trying to do all these things at once.
So the worry about it can be dissolved by knowing that it's all going to pass, thinking "Whether I can do all of them all at once, or whether I can do only one and four of them don't get done, it's still just going to pass, it's going to pass." When we bring in the thought of impermanence, this helps us to have more equanimity. Now underneath all that is to regularly contemplate that we can't fix everything. Even the Buddha couldn't do that either, his own cousin tried to kill him. When we contemplate that we can't fix everything, this ties into the compassion and the equanimity reflection, that no matter how great and wonderful and smart we are or the Buddha was, we can't fix everything. So when we are overwhelmed with things and we're not sure we're going to get everything done, always remember that even if we are perfect we're not going to be able to fix everything. That gives us more of a balanced mind, to know that, "It's OK, I just do the best I can, one at a time."