There's thinking about things, and then there's "over" thinking about things. The problem with over thinking is that often it results in getting thoughts stuck in almost a feedback loop where emotions just start building on top of each other until they become unmanageable.

I've found that unhealthy over thinking usually occurs when you stop fact checking, and just start building larger and larger worst case scenarios in your mind, without stopping for a reality check.

Like autotelica, I think a lot at work, problem solving. But, even then, there comes a point where it's time to step away and get a fresh perspective if you start finding yourself stuck in a single thought pattern that isn't allowing you to progress forward.

I think that's the important thing to consider when you look at whether thinking about things is healthy or unhealthy. Are your thoughts allowing you to progress forward, or are you just getting stuck in a loop where your emotions just keep building up? I know it's hard to stop the unhealthy over thinking. Sometimes, I have to verbally tell myself "Stop! You're getting stuck." When I hear it out loud, it lets me break that cycle, and then I can ask myself - what do I have control over? what do I know is true? what do I need to fact check with someone else? am I moving forward by thinking about this, or am I just getting stuck? Asking those questions usually lets me determine whether I'm problem solving or just getting stuck in self-defeating thoughts.

So, to me, it sounds like your over thinking is the feedback loop type...the more you think about things, the more your emotions build, which is probably rather unhealthy.

You state that "When u have nothing else to base your thoughts off of, of course you are going to speculate and assume." That's when you should fact check, rather than continuing to speculate. You stop, find out what is true, and try to reframe your thoughts. If you can't fact check right away, then maybe you need to tell yourself "stop...I don't have the answers right now. I need to find out what is true, which means I have to wait."