I believe I understand your type of obsessive thoughts. I too worry about things like mortality and he meaning of it all and my place in the universe. I find myself doing it too much when my OCD is at its worst. I have been doing it a lot lately.

My cycle goes from worrying about stresses at work and other everyday stresses and can work its way into the territory of what you're referring to.

I have no perfect fix for this except keeping very busy with fun things. Some meds work well, but I also exercise a lot. I do yoga and bodybuilding. They help relieve stress and help boost endorphins.

I hope some of this helps you even if you know that others suffer from it as well.