luckedog I can only give you my childish slacker advice. But I can tell you that you cannot worry enough to make any difference. Either do something that helps to resolve the problem, or put it out of your mind. Some problems are not problems, they are predicaments. Predicaments are irresolvable. My mum is 89, (but she lies and tells everyone she is 82), it takes a lot of effort from time to time to help her out. But I have pretty much resolved that I cannot live her life for her, I cannot make her younger, and I cannot make her health more robust. I help where I can, and accept help when it is offered.
Putting something out of your mind is no simple task. You cannot not think about something. The only thing I can do is think about something else, I know I sound like a broken chant, but meditation is sometimes the only peace I get. Neomarxist wrote a great post the other day how alcohol was the reset button for his mind, and it was true for me too. It was a powerful way to escape and reboot. Away from chemicals, the reboot is much more subtle.
One thing that has worked for me in the past was hypnotherapy. It was a brief sober period in my life a few years ago, and I was living in a world of sh!t. Solid walls of stress were making me a basket case. She gave me a visualization that was very helpful. She put me into trance and had me visualize my self on the beach (a favorite place of mine) and I went around collecting things on the beach and putting them into a backpack. The things were a metaphor for my troubles and worries. Once I filled the pack, she had me close it, place in on the sand and walk away. It was about giving myself permission to detach for awhile and get some perspective. A month later my father died and I chose to return to the world of sh!t with a bottle in hand... Oh well, I still drag out that visualization form time to time. I hope you find a non-chemical way to reset.