If I thought things for no reason at all my thoughts and feelings would be unconnected to any efforts or lack thereof on my part.

This scenario provides no preferred course of action, and can thus be safely discarded from this and all future considerations. Indeed, if it is correct, I cannot discard it, so I am safe in discarding it even if my sole aim is truth, rather than preferred courses of action.

Occam's razor. There are patterns in your thoughts that are very unlikely to exist by coincidence. It's more likely that the pattern is a result of an underlying process. At least, that's why I think that I think things for a reason.