First of all, I would like to give my apologies for being sometimes slow on responses to emails and other sorts of communication. Last weeks were throwing new challenges, dealing with which takes a little bit of time. I'll catch up.
In case you are interested, here are a few random ideas that have proven to be helpful in handling such situations. These ideas were reiterated so many times, that it's no longer possible to point to the original author.
Don't try to be perfect in your decisions. You are human and small errors are inevitable. Besides, every single decision is worthless by itself (just like any "brilliant" idea). Only through the continuous and careful application of effort, something worthy can be achieved.
Continuous chain of good decisions will beat perfect plan any day (simply because you can adapt and keep on going). Likewise, good execution can be more important than any great idea alone.
Delegate. No matter how smart and talented we consider ourself to be, alone we are not able to handle and achieve as much as a team. Hence it is our duty to ensure that incoming challenges are balanced against the entire team. Our purpose is not to keep everybody under 100% load (e.g. by assigning tasks to people who are less efficient in handling them), but to ensure maximum efficiency of the entire unit.
Focus. Keeping multiple projects in your head at once is likely to drive you insane, cause insomnia, burnout or do worse. So try breaking entire problem field of your division or company into separate contexts. They can be really diverse: starting from accounting, HR management and up to long-term tech RnD. More often than not, you will find that tackling a specific problem involves just a single context. So you can keep only one context in your head most of the time, switching between them, as your day moves forward.
Arrange all tasks within this context in a queue, putting most painful ones upfront. Don't be afraid to drop tasks or change their priorities, if environment changes.
If you are tired but don't have time to rest - switch contexts. If you are exhausted but don't have time to rest - stop complaining and find some time. Full personal burn-out is far more expensive than a little bit of rest.
Adapt to changes on the battlefield. You would be surprised by the amount of resources wasted on projects even after they are doomed. Wars are not won by the sheer force, unless you are USA (and even States encountered some issues while bringing democracy to countries which didn't have serious fire-power but had population willing to take benefit of every hill, forest and trick in the book).
By being willing to accept that our initial plan is imperfect and adapt, we can reduce risks, save resources and potentially leverage new opportunities. Think "Instagram" or "Apple".
People are the only reason things happen around, don't forget about it. Universe was empty without purpose till humanity showed up bringing purpose along (with a noticeable degree of chaos).
It might be tempting to forget about people and focus on a single technology, idea, concept or code. However, by doing that we risk missing the whole point and actually undermining our own efforts.
For example, writing complex code without unit tests or documentation is often perceived as a sign of outstanding hacker or even a guru. Sometimes this even is worth it. However, more often than not, other people will have to maintain such code for years. If it is the case, then it is egoistic not to think about them. Code can have stronger positive impact if we put putting additional effort in making it helpful and friendly. It is much harder to do that, than delivering egoistic "easy to write and hard to read" code. Result will have greater long-term impact, though.
Same principle applies to all the other things we do in our everyday lives. This is not even an altruism, but merely common sense and adequate long-term thinking.
And the last one - Don't stop and keep pushing.
PS: I don't follow these quotes every single day (not strong enough for that). However, continuously trying to do that - helps to keep moving.