Do you think too much about small problems until they become bigger than they really are? Do you think so much about positive things until they no longer look so positive? Thinking about things is fine, but becoming an excessive thinker makes you stay still in life, you self-sabotage.
When I think a lot about something, I wonder if that mattered to me in 2 or 3 weeks or even 1 year, this makes me get out of that situation and focus my energy on something that is important. I also set time limits to decide, it does not matter if the decision is small or big.
In the life we lead it is difficult to avoid stressful days, but they can be minimized, try to start the day well, a stressed morning leads to an equal day, try not to consume negative news while you go to your work that generates pessimistic thoughts, instead read something stimulating during breakfast.
Take small steps forward and become a person of action, set deadlines and focus, you'll see that it works, if you do a habit you will not feel like fleeing.