Human psyche loves implied causality and despises anything which incurs a cost function (extra effort)
“I roamed across the city all day visiting different local sites; however in the evening I found my wallet missing”
If this statement gives you a negative connotation(wallet getting stolen etc.), it means your impulsive mind has automatically formed a judgement on the causality of this event based on whatever past information it has (mind recollects the negative ones more quickly) although there’s nothing indicative in the statement itself.
This is precisely what happens when one is anxious/overthinking. The key here is to remember there’s a less intuitive, more logical part of our mind (system 2, as Kahneman describes) which needs to be given priority in cases where one doesn’t have a concrete past history to rely on.
And while overthinking, more often than not the answer lies with Occam’s Razor – The simplest reason is usually the best!