Take stock of what is and what is not in your control. There are a lot of things in life that are unfair that are outside of our control.
If the thing is in your control, take stock of what actions you can take to change the thing to better suit your desired outcomes.
This advice may seem trite, but it’s been repeated for generations because it is always like this in some capacity. Life will throw shit at you. Your job as a person seeking a happy healthy life is to learn how to react and respond. If it’s out of your control, you have to make the best of it. Even if it sucks.
There are people happily fighting cancer. There are happy paraplegics. There are happy people in Gaza (not many, but I guarantee there is someone finding the silver lining in a real hell scape).
Learn to accept the things you cannot control. Learn to act in the things that are within your control.