When it comes to focusing, set your intention and attention on what is in your control and distinguish it from what is not.
The next time you face a difficult situation and feel reluctant, find out what you can control and what you can’t. Write them down. The part you can control is the part you must focus on.
There are many examples to internalize this concept, here is one: You should not focus on avoiding losing the game but instead playing to the best of your ability. A win is only a by-product.