Make a list. Put everything that’s on your mind, that’s causing you stress, on one list (text document or paper list): current or upcoming projects, small tasks, errands, chores, trips, relationship problems, parties, meetings, holiday plans, shopping you need to do, emails that are weighing on your mind, a load of incoming requests, etc. No need to order them, just throw everything on the list. It doesn’t need to be complete — as you think of other things, you can add them.
Make notes. Put a little note next to each item — can you eliminate the item? Can you ask someone to cancel? Can you get out of a commitment? Can you just let something go? Can you postpone something until you have more time? Can you ask someone else to do it or get help? Or is this a high-priority task that needs to go on your Must Do List today or tomorrow? Does it deserve a block on your schedule? Can you block off some time today to churn through the smaller tasks on the list? Also: do you need to have a conversation with someone, to resolve a conflict that’s bothering you? Just make quick notes next to each, for how you’ll resolve the item.
Prefer elimination. If you can get the item off the list, try to cancel, eliminate, delegate, or at least postpone. Try to clear up space, so that you have less on your plate. Take a few minutes now to email or call people to cancel or postpone. This will give you the mental and time space you need.
Resolve to resolve. For the rest of the items that aren’t eliminated or postponed, make time to deal with them. Block off time in your schedule to do your high-priority tasks, to resolve issues, to churn through the smaller tasks that can’t be eliminated.