This is actually a really interesting question, although I am not sure of the exact context of what you are asking about. That is, thinking about "thoughts and feelings" in terms of "existential dread" and wondering "why am I here" is one thing. Thinking through "should I buy a house this year or keep renting a little longer?" seems like quite a different thing.

I can offer three vague suggestions, all of which concern things that I am aware of, but don't necessarily have a lot of personal experience with.

In the world of mental health, there is a technique called Cognitive Behavioral Therapy[1], which - as I understand it - is heavily rooted in the idea of breaking thoughts/feelings/emotions down in rational terms and thinking (eg, "cognition") about them in rational terms. If someone believes they have serious mental health issues, they should probably consult a professional, but outside of that context there are plenty of CBT books that you can find at Amazon or B&N to get some exposure to the ideas / techniques.

Getting away from the mental health angle, if we're just talking about making good decisions about more concrete things (buy a house or not, change jobs or not) where financial factors and such-like are key elements, then you might find some value in something like A3 Thinking[2].

Taking an even broader view, there is an entire science of "Decision Theory" (or "Decision Science")[3] which deals with detailed mathematical modeling of decisions and techniques to make optimal decisions. This comes in more for things like "I'm a company and I need to decide whether to open a new factory in North Carolina and a new distribution hub in Colorado, or open a smaller factory in Wyoming and three distribution hubs in the Northeast", blah, etc. This brings in elements of Game Theory, Optimization, Operations Research, etc.

[1]: https://en.wikipedia.org/wiki/Cognitive_behavioral_therapy

[2]: https://planet-lean.com/what-is-a3-thinking/

[3]: https://en.wikipedia.org/wiki/Decision_theory