There are moments of inspiration that bring a great idea, and life is better for the innovation. But in the day to day living of life, originality is best used in moderation.
When the routine of work, school, groups, clubs, and appointments have you stretched to your limits; there is no good reason to not use a good idea or modern convenience available. The best memories are not going to be made by stressing yourself out.
Buy the costume off the rack. Get the birthday cake from the grocery store. Search the internet for decoration ideas. Give money or gift cards. It is alright.
At the end of the day, it is the attitude of the people you spend time with that will be remembered. If coming up with new recipes and creating your own party favors is your happy place, do that. If you find yourself dreading gatherings; look at why you feel that way. If planning and prep time lead the list; simplify, minimalize, delegate.
Put the happy back in your holidays.