All too often I see people who allow themselves to be stressed about things that are beyond their control. I am not saying we should all be soulless robots, but what is the point in stressing out about what someone else is doing / has done, for example? You cannot affect their behaviour. You can only change your own, so it’s wasted energy.
Don’t take on other peoples emotional baggage, only take on your own, things that you have direct control over.
You will never achieve a different goal by constantly doing the same things. You will never gain what you don’t have, without sticking your neck out, taking a risk, and just going for it.
Now the trick is to work out what you CAN influence or change, and what is beyond your control. After you work that out, you can set about either offloading the stress, or dealing with the challenge.