Should I stop negative thinking, like imagining things then thinking there going to happen ?

Okay well this I think I'm becoming superstitious, I don't like it neither :( well I keep thinking if I think something bad will happen it will happen, say I have a random thought about something And say I think it in my head I think something will happen to them because I've thought about it happenining to them, after I have thought about something bad happening to them it stays on my mind, it really works me up is there any truth in this