Break it down
Once you realise the magnitude of what you’re about to do, hyperventilation is only a moment away. Get back on top by sitting down for a minute and taking the task apart. Once you see it in sequence, it can be much easier to achieve. Yes you might need to blog, then tweet, then share on Facebook, then read six articles on blogging, then respond to comments, then find something to write for the next day, but it doesn’t all need to be done at once. Break it down and spread it out.
Every writer becomes overwhelmed -- relax. Break each project and task into itty bitty pieces.
IQTELL (free) really helps -- it helps me to break down everything into the smallest possible chunk I can complete in 15 minutes or less.