To fail at everything you want to do, take a moment and think about the thing you want to do. It can be anything. A presentation, launching a product, or even taking a class. Great.
Now, imagine one thing that can go wrong. Maybe your slides get accidentally deleted and you can't continue your presentation. Right after you launch your product, you discover a similar product with a similar name, and a better offering. Or the class turns out to be too hard and you don't understand a thing. Great!
This future you are imagining is really not working for you, and would likely be embarrassing. So the next step is to take that future and bring it into the present. Be embarrassed by your speech today. Be frustrated about the product today. Feel inadequate about your class today.
You will feel the stress and emotions of these failures today and chances are you will give up right away.
I hope you are not actually following my advice, these are terrible things to do. But that's a pattern I see everyday. I see people feeling inadequate at their job before they do something inadequate. I see people skipping class because they think they won't understand it anyway. I see people wanting to quit their job because they think their boss is going to fire them anyway.
These problems come from imagined scenarios that will most likely never happen. But we are consuming all the frustrations that come with the problem well before the problem occurs. Do not prepare to be hurt. In fact, there is no such thing as preparing to be hurt. It's not like you will feel better after.
Only prepare for things you can change. If you think someone might have the same product, do some research before you build the whole thing. If you think some technical issue might happen during your presentation, do a mock presentation, rehearse. If you think the class might be too complicated, look through the prerequisite, learn the material first. Prepare for the things you can change.
Avoid trying to predict a future. In fact, if you want to be wrong, try predicting the future.
But if you really want to fail, then suffer the consequences of imagined scenarios today.