There's a saying, that if you want to eat an elephant, you have to start with one bite.

[....]

That is to say...you do not have to make so many decisions all at once. Start by simply choosing what you'll have for breakfast that day, or add something different to your outfit from the costume shop. Such decisions are consequential to you, but in the overall scheme of those of us who are used to constantly making decisions, they are completely regular and most of the time we hardly think about it before doing so.

And...if you need a respite from such things, you can always ask someone to choose for you once in a while.