Similar to you mine is stress -- if I'm stressed about work or anything happening in my personal life everything plummets. I can't focus my attention in a productive way. I can't sleep well because my brain is full of worries and negative emotions which don't help my creativity. Except for maybe emo lyrics / sad poetry.
Stress outside of work, anything that's causing my mind to be worried / distracted from what I'm working on inevitably effects how creative I am.
Trying to separate personal stress from work can also be hard when working remotely because you're sometimes in the environment that causes you stress.
Not knowing what to do or how to do.
And yeah distractions of knowing more than I need while searching for a topic on internet, drifting away from the main topic. This take away a lot of valuable time and mental energy.
I'm not fully sure what blocks my creativity. I've noticed that I am most productive when I am a little cold, a little hungry and without distractions. Like Waking up, getting to computer and starting to work. Six to nine hours go almost nonstop, and then I start to realize I would need to take care some of my basic needs.