Taking too long thinking about something could allow you to miss out on many chances, missing the boat as it were. I am not talking about for the good of mankind and world peace (that has to be thought through, agreed) just in everyday life e.g. taking too long thinking on a decision or an idea that might have made a fortune (someone pips you to the post or steals it) or an interesting job offer lost because you didn't act on it sooner or taking too long to ask someone special for a date. It's ok thinking as long as it isn't negative thinking.