When faced with a big task, I usually feel overwhelmed. But if I take a step back and focus on a singular thing that needs to happen, it makes it far more managable. The first step is always the hardest, but once taken, you've overcome a the mental block of seeing the whole forest.
For instance, after a dinner party, the stack of dishes seems insurmountable. But if you focus on the first dish, then the next, then the next...pretty soon the entirety of the effort seems manageable.
In my professional life, I have to build a lot of excel models - many of which are complex and take a long time. This, again, seems overwhelming. But I start by putting something - anything! - in a cell. Then I build out a row of headers. Then the column headers and a formula or two. Then iterate on that. Soon, the insurmountable task has been made possible by SIMPLY DIVING IN. And once you have something to iterate on - even if its "bad" - it's mentally easier to make changes than start from scratch.